5th Theodor Escherich &

2nd AMICI

Joint Symposium

8th - 9th November 2018

Neuer Med Campus, Neue Stiftingtalstraße 2

Medical University of Graz, Austria

ABSTRACT BOOK

If you do ’t like i ro es, you’re o the ro g pla et

(Stewart Brand, adapted)

In behalf of the organizing committee of the 5th

Theodor Escherich & 2nd

AMICI Joint Symposium

2018 we cordially welcome you at the Medical University of Graz.

We are very pleased with the high number of renowned national and international scientists

o eri g the topi s i ro io e a d a er , i ro io e a d utritio , i ro io e a d e iro e t , egle ted e ers of the hu a i ro io e , i ro iota odulatio a d the

pla t i ro io e that ha e a epted our i itatio to speak.

We will have more than 200 guests from Austria and Europe, interested interdisciplinary microbiome

research. The new Campus at the Medical University in Graz provides an excellent venue for this

event, and we are convinced that the wonderful atmosphere in this building will support personal

exchange and discussion amongst young researchers and PIs.

We are particularly thankful for the fruitful interaction with the Austrian Microbiome Initiative

AMICI, serving as an excellent networking platform for microbiome research – resulting in this joint

adventure this year!

We are extremely grateful for the generous support from our sponsors and industry partners.

We are looking forward to a very fruitful meeting,

The local organizing committee

Gabriele Berg

TU Graz

Gregor

Gorkiewicz, MUG

Christoph

Högenauer, MUG

Robert Krause,

MUG

Christine Moissl-

Eichinger, MUG

www.medunigraz.at/microbiome

Sehr geehrte Damen und Herren, liebe Kolleginnen und Kollegen!

Bakterien, Viren, Archaen, Parasiten und Pilze – unseren Körper teilen wir mit Billionen Bakterien, die Mundhöhle, Haut und Darm besiedeln. Rund eineinhalb Kilogramm unseres Körpergewichts macht das Mikrobiom aus. Das Wissen um die Relevanz des Mikrobioms für die Gesundheit unseres Körpers wurde in ihrer

Bedeutung lange Zeit unterschätzt. Das hat sich mit der Entwicklung neuer Methoden vor rund 15 Jahren deutlich gewandelt. Mittlerweile ist die Erforschung

des Mikrobioms ein sich rasch entwickelndes Forschungsfeld mit Relevanz für viele Bereiche unseres Lebens – von Humanmedizin, über Veterinärmedizin, Mikrobiologie, Umweltbiologie bis zur Toxikologie. In allen diesen Bereichen

wurden wichtige Zusammenhänge mit dem Mikrobiom gefunden.

Das diesjährige 5. Theodor-Escherich und 2. AMICI Symposium trägt dieser rasanten Entwicklung in mehrfacher Hinsicht Rechnung. Die gemeinsame

Veranstaltung bringt Forscher aus unterschiedlichsten Bereichen zusammen für Wissensaustauch, Inspiration, Vernetzung und Schaffung von Synergien. Die

Themen umfassen viele der derzeitigen „hot topics“ im Bereich der Mikrobiom-Forschung: Krebs & Mikrobiom, Mycobiom, Archaeom, Gastrointestinale

Erkrankungen, Ernährung, Fäkale Mikrobiota-Transplantation und Pflanzenmikrobiom. Die Diversität der Themen reflektiert die bunte Vielfalt an

Expertise, die sich in Graz versammelt zum Wissensaustauch. Posterpräsentationen und ausgewählte Vorträge zu aktuellen, österreichischen

Forschungsergebnissen zeigen die positiven Entwicklungen in der Mikrobiomforschung zusätzlich auf.

Ein Grundstein für diese erfreuliche Entwicklung in der österreichischen Mikrobiom-Forschungsgemeinschaft wurde vor 2 Jahren gelegt mit der Gründung

der Austrian Microbiome Initiative (AMICI). AMICI verbindet neun unterschiedliche Fachgesellschaften, um Expertise in diesem Bereich zu bündeln

und eine Plattform für den Wissens- und Ressourcenaustausch zu schaffen. Innerhalb dieser kurzen Zeit hat die neue Gesellschaft im In- und Ausland

Anerkennung gefunden, hat Forscher bei der Entwicklung von Projekten und Beantragung von Forschungsförderungen unterstützt und das Thema für Laien bis zu Experten sichtbarer gemacht. Einen Überblick über die Aktivitäten und

Expertise von AMICI finden Sie auf unserer Homepage (http://www.microbiome.at/de).

Das zweite AMICI Symposium ist somit ein weiterer Schritt zur Vernetzung von Kollegen und Freunden im Bereich der Mikrobiomforschung. Ich freue mich,

dieses Symposium mit ihnen zu verbringen!

Prof. Dr. Christoph Steininger

Präsident AMICI

8.15- 9.00 Registration and set-up

9.00- 9.10 Lecture hall: Opening and welcome note

9.10- 10:10 Lecture hall: Session 1: Microbiome and cancer

Chairs: Margit Neger & Buck Hanson

9.10 (30 min) INVITED: “Gut microbiota and colorectal cancer” Paul O`Toole, University College Cork, Ireland

9.40 (30 min) INVITED: “Microbes, Microbiota and Cancer” Julia Drewes, John Hopkins University, Baltimore, USA

10.10- 10:50 Lecture hall: Session 2: Nutrition and Environment I

Chairs: Jovana Mihajlovic & Sabrina Mörkl

10.10 (20 min) INVITED: “Toxins and microbial metabolites in food: a Trojan horse?” Doris Marko, University of Vienna, Austria

10.30 (20 min) INVITED: “New functions of the core human microbiota: Metabolism of

a vegetarian diet compound in the gut” Alexander Loy, University of Vienna, Austria

10.50- 11.20 Coffee break and posters

11.20- 12:50 Lecture hall: Session 3: Nutrition and Environment II

Chairs: Markus Eder & Angela Horvath

11.20 (20 min) INVITED: “Intestinal microbiota and barrier: A trigger of aging?” Ina Bergheim, University of Vienna, Austria

11.40 (20 min) INVITED: “Studying interactions between herbal medicinal products

and human gut bacteria” Eva Pferschy-Wenzig, University of Graz, Austria

12.00 SELECTED CONTRIBUTIONS (10 min each):

“Prebiotic intervention with partially hydrolyzed guar gum (PHGG) – symptomatic, taxonomic and metabolomic outcomes from the prospective PAGODA trial” Simon Jakob Reider, Medical University Innsbruck, Austria

“Complementary intestinal mucosa and microbiota responses to caloric restriction” Kalina Duszka, University of Vienna, Austria

“Profiling the apple microbiome for health issues” Birgit Wassermann, Technical University Graz, Austria

“Evaluating the selectivity of prebiotics: Inulin as a case study” Alessandra Riva, University of Vienna, Austria

“Urinary and vaginal microbiome in premature labor” Manuela-Raluca Pausan, Medical University Graz, Austria

12.50- 14.50 Lunch break, posters and poster pitches

13.30 (~ 40 min) Lecture hall: Short presentation of posters: “Poster pitches” (1 min ea)

Program: 5th Theodor Escherich & 2nd AMICI Joint symposium on Medical Microbiome Research

Thursday, 8 November 2018: morning

14.50- 16:00 Lecture hall: Session 4: Neglected members of the human microbiome

Chairs: Alexander Mahnert & Julian Taffner

14.50 (10 min) SELECTED CONTRIBUTION

“The human archaeome”, Kaisa Koskinen, Medical University Graz, Austria

15.00 (30 min) INVITED: “Methanoarchaea as part of the human microbiome:

Friends or Foes?” Ruth Schmitz-Streit, University of Kiel, Germany

15.30 (30 min) INVITED: “Microbiome/Bacteriome Interactions: Role in Health and

Disease” Mahmoud Ghannoum, Case Western Reserve University, USA

16.00- 16.20 Coffee break and posters

16.20- 17:40 Lecture hall: Session 5: Microbiomes of humans and plants/various topics

Chairs: Kaisa Koskinen & Vijaykumar Patra

16.20 (30 min) INVITED: “The inter-connected microbiome: from plants to human”

Gabriele Berg, Technical University of Graz, Austria

16.50 SELECTED CONTRIBUTIONS (10 min each):

“Plasmid DNA contaminant in molecular reagents” Christoph Steininger, Medical University of Vienna, Austria

“Is the gut-lung axis bi-directional? Alternations of the gut microbiome in mice with allergic lung disease” Irma Schabussova, Medical University Vienna, Austria

“Changes in the cutaneous microbiome in the course of allogeneic hematopoietic stem cell transplantation” Nadine Bayer, Medical University Vienna, Austria

“Increased Staphylococcus aureus abundance in cutaneous squamous cell carcinoma confers microbial growth stimulus for tumor cells” Nanditha Madhusudhan, Medical University Graz, Austria

“Antibiotic-associated secondary IGA-deficiency enhances susceptibility to Pseudomonas aeruginosa pneumonia” Oliver Robak, Medical University Vienna, Austria

17.40 End of day 1, closing remarks

For invited speakers only: Speakers’ dinner

Program: 5th Theodor Escherich & 2nd AMICI Joint symposium on Medical Microbiome Research

Thursday, 8 November 2018: afternoon

8.15- 9.00 Registration and set-up

9.00- 10:30 Lecture hall: Session 6: Microbiota-Modulation Chairs: Christoph Högenauer & Barbara Jelusic

9.00 (30 min) INVITED: “Stool banks for fecal donation - A necessity for the future” Josbert Keller, NDFB, The Netherlands

9.30 (20 min) INVITED: “Microbiota Modulation as a new treatment option for

inflammatory bowel disease - ready for clinical practice?” Patrizia Kump, Christoph Högenauer, Medical University Graz,

Austria

9.50 (20 min) INVITED: “How can we change the intestinal microbiota by fecal

microbiota transplantation, antibiotics or probiotics?” Philip Wurm, Medical University Graz, Austria 10.10 SELECTED CONTRIBUTIONS (10 min each):

“Microbiome, Molecular Clock and Mood in affective disorders” Susanne Bengesser, Medical University Graz, Austria

“Immunomodulation of the Human Gut Microbiome via Bacterial Membrane Vesicles” Paul Kohl, University of Graz, Austria

10.30- 11.00 Coffee break and posters

11.00- 13:00 Lecture hall: Session 7: Plant microbiome Chairs: Wisnu Wicaksono & Lisa Krug

11.00 (20 min) INVITED: “The role of the seed microbiome of barley for plant

performance” Michael Schloter, TU Munich, Helmholtz Center Munich, Germany

11.20 (20 min) INVITED: “Human pathogens in plant production systems” Leo van Overbeek, Wageningen University, The Netherlands

11.40 SELECTED CONTRIBUTIONS (10 min each):

“Microbiome and metabolome diversification in medicinal plants” Martina Köberl, Technical University Graz, Austria

“Three are better than one - in silico, in vivo and in vitro analysis of the antibiotic resistome of a moss microbiome”

Melanie-Maria Obermeier, Technical University Graz, Austria

“Naturally occurring antibiotic resistances in the microbiome of leafy greens” Tomislav Cernava, Technical University Graz, Austria

12.10 (20 min) INVITED: “Biosafety risk from the plant microbiome” Lise Korsten, University of Pretoria, South Africa

12.30 (20 min) INVITED: “The rhizosphere microbiome under extreme conditions” Dror Minz, Agricultural Research Organization ARO, Israel

12.50 Poster awards, Yakult award for best contributed talk

Closing remarks and end of the symposium, sparkling wine reception and goodbye!

Program: 5th Theodor Escherich & 2nd AMICI Joint symposium on Medical Microbiome Research

ABSTRACTS | CONTRIBUTED TALKS Session 3: Nutrition and Environment II Thursday 8.11.2018, 11.20-12.50

Prebiotic intervention with partially hydrolyzed guar gum (PHGG) – symptomatic, taxonomic and metabolomic outcomes from the prospective PAGODA trial Reider SJ, Moosmang S, Trgovec-Greif L, Tragust J, Tragust S, Przysiecki N, Sturm S, Tilg H, Stuppner H, Rattei T, Moschen AR Christian Doppler Laboratory for Mucosal Immunology, Dpt. of Internal Medicine, Medical University Innsbruck, Austria

INTRODUCTION: Dysbiosis is associated with various disease states. Prebiotics may help to improve microbial compositions. Partially hydrolyzed guar gum (PHGG) is one out of several prebiotic regimens used in clinical practice. The underlying mechanisms associated with prebiotic interventions remain however elusive. We performed the prospective multi-omics PAGODA study aiming at deciphering the mechanistic underpinning between a prebiotic intervention with PHGG and clinical, taxonomic, and metabolomics outcomes. METHODS: The study included 19 healthy volunteers that followed a three-phase schedule: three-week-introduction without intervention, three-weeks of intervention with PHGG, and three weeks wash-out follow-up after stopping PHGG. Blood, urine and fecal samples along with questionnaires on symptoms, stool frequency and consistency (Bristol stool scale score) were collected weekly. V1-V3 and V3-V4 regions of bacterial 16S-DNA from fecal samples were sequenced. Nuclear magnetic resonance (NMR) spectra from fecal sample extracts were acquired on a Bruker NMR-spectroscope. RESULTS: PHGG administration resulted in increased stool frequency paralleled by reduced consistency. This laxative effect was significantly stronger in male participants. PHGG significantly increased diversity that persisted even after stopping fiber resulting among others from expanses in Lachnospiraceae. NMR spectroscopy identified more than 150 fecal signatures that were significantly associated with PHGG intake. CONCLUSIONS: The PAGODA study shows that a short-term fiber-based intervention induces both short-lived and prolonged alterations of gut microbial structures along with changes in microbial metabolites. Numerous significant changes in NMR spectra between study periods may indicate that even a simple prebiotic intervention can induces multifaceted alterations within the microbial metabolite profile.

Complementary intestinal mucosa and microbiota responses to caloric restriction Kalina Duszka, Sandrine Ellero-Simatos, Ghim Siong Ow, Marianne Defernez, Eeswari Paramalingam, Adrian Tett, Shi Ying, Jürgen König, Arjan Narbad, Vladimir A Kuznetsov, Hervé Guillou, Walter Wahli Department of Nutritional Sciences/University of Vienna, Vienna, Austria

The intestine is key for nutrient absorption and for interactions between the microbiota and its host. Therefore, the intestinal response to caloric restriction (CR) is thought to be more complex than that of any other organ. Submitting mice to 25% CR during 14 days induced a polarization of duodenum mucosa cell gene expression characterised by upregulation, and downregulation of the metabolic and immune/inflammatory pathways, respectively. The HNF, PPAR, STAT, and IRF families of transcription factors, particularly the Pparγ and Isgf3 genes, were identified as potentially critical players in these processes. The impact of CR on metabolic genes in intestinal mucosa was mimicked by inhibition of the mTOR pathway. Furthermore, multiple duodenum and faecal metabolites were altered in CR mice. These changes were dependent on microbiota and their magnitude corresponded to microbial density. Further experiments using mice with depleted gut bacteria and CR-specific microbiota transfer showed that the gene expression polarization observed in the mucosa of CR mice is independent of the microbiota and its metabolites. The holistic interdisciplinary approach that we applied allowed us to characterize various regulatory aspects of the host and microbiota response to CR.

Profiling the apple microbiome for health issues Birgit Wassermann, Tobija Glawogger, Clara Duft, Paula Fürschuss and Gabriele Berg Technical University/Institute of Environmental Biotechnology, Graz, Austria

Plant health is intensively connected with the inherent microbiome. In case of raw-eaten fruits and vegetables, plant´s microbiome can also affect human health. The present study aims to reveal the structure of the apple microbiota and to identify their potential impact on plant as well as on human health. For that easo , 1 S RNA a pli o li a ies of A let apples p odu ed o ga i ally healthy a d affe ted y Venturia

inaequalis (Cooke) G. WINT.) or conventionally were studied and native micro niches were visualized by FISH Confocal Laser Scanning Microscopy. All microhabitats of the apple fruit feature high microbial diversity, and the microhabitat was found to be the main driver of the microbial composition. Network analyses indicate a high abundant core microbiota, shared by all apples, but the relative abundance of those taxa highly varies between organically and conventionally managed ones, whereas infestation with the fungal pathogen V.

inaequalis had no significant impact. Organically managed farms suffer from lacking strategies to combat infestations of V. inaequalis and Botrytis cinerea PERS. Therefore, a strain library was established comprising 1,270 bacterial isolates from different apple microhabitats; among them, 174 and 164 isolates possess antagonistic properties towards V. inaequalis and B. cinerea, respectively. These antagonistic isolates will be further evaluated regarding their capability to biologically control diseases. According to viable cell counts, the consumption of one apple includes an uptake of 120,000 bacteria. The data can be applied to portray the contribution of the microbiota for quality and safety of apples and provide new concepts for disease prevention in organic agriculture. Moreover, as the results were obtained in cooperation with pupils, novel results from microbiome research can be translated into society.

Evaluating the Selectivity of Prebiotics: Inulin as a case study Alessandra Riva, David Berry Department of Microbiology and Ecosystem Science, University of Vienna, Austria

Prebiotics are defined as a non-digestible dietary ingredient that selectively promotes the growth of beneficial gut microorganisms. The selectivity of prebiotics for promoting growth of a restricted set of microorganisms has, however, not been systematically studied. In the present project, we used state-of-the-art Raman microspectroscopy and Raman activated cell sorting in order to evaluate which microorganisms are stimulated by the popular prebiotic inulin. Anaerobic incubations of fecal microbiota amended with inulin and in the presence of heavy water (D2O), a marker of cellular activity, revealed substantial inter-individual variation in the response to inulin. This suggests that not all microbiotas are alike in their ability to metabolize inulin. We then sorted deuterium-labeled cells using a Raman microfluidic system and were able to isolate and cultivate inulin-stimulated strains. Using this approach, we recovered a diverse collection of strains belonging to the major phyla of the gut microbiota, including Firmicutes, Bacteroides, and Actinobacteria. These results indicate that inulin is not as selective in promoting growth of specific taxa as has been previously suggested, and provides an experimental framework for determining the selectivity of other proposed prebiotics.

Urinary and Vaginal Microbiome in Premature Labor Manuela-Raluca Pausan, Evelyn Jantscher-Krenn, Eva-Christine Weiss, Vassiliki Kolovetsiou-Kreiner, Christine Moissl-Eichinger Department of Internal Medicine, Medical University of Graz, Austria

Premature labor is associated with genitourinary infections and periodontal disease, but definitive etiology still remains unclear. Traditionally ascending infections from the vagina are thought to cause preterm labor, but cannot explain all cases. Studies have shown that the microbiome at different body sites (such as gut and vaginal) changes during pregnancy and these changes might have a role in regulating the timing of birth. Furthermore, evidence is accumulating that the healthy urinary tract also harbors resident microorganisms, and that urinary microbial communities might be associated with a certain health status. The objective of this project is to assess whether urinary microbiome and/or human milk oligosaccharides (HMO) are altered in preterm labor and to investigate the interaction of urinary HMO profiles with urinary and vaginal microbiome, and to assess differences in preterm labor of the urinary and vaginal microbiome. The urinary and vaginal microbiome have been explored using a NGS approach based on amplicon sequencing, followed by a qPCR approach to determine the number of 16S rRNA bacterial genes. The HMO composition of blood and urine has been analyzed using HPLC-FL. Preliminary results show no great changes in the vaginal or urinary microbiome between subjects with pre-term labor as compared to the control group. Slight changes in specific genera have been observed for both the vaginal and urinary microbiome, for example an increase in Lactobacillus jensenii and Ureaplasma sp. in vaginal microbiome in subject with preterm labor and an increase in Finegoldia sp., Lactobacillus gasseri and L. jensenii in urine. Session 4: Neglected members of the human microbiome Thursday 8.11.2018, 14.30-15.40

The human archaeome Kaisa Koskinen1,2, Manuela Pausan1, Alexander Mahnert1, Marcus Blohs1, Christine Moissl-Eichinger1,2 1Department of Internal Medicine, Medical University of Graz, Austria

2BioTechMed-Graz, Austria

The human microbiome is composed of trillions of microbes from all three domains of life. However, most human microbiome studies focus on Bacteria, and the presence of Archaea is often overlooked. However, in certain body sites they can comprise a substantial share of the microbiome and account for important functions for human health – and possibly disease. The current knowledge about the human archaeome is largely restricted to four methanogenic archaea isolated from feces and oral mucosa, and fragmented information from microbiome studies, as the standard methodology is often insufficient to detect them. Our essential goal is to uncover the diversity, quantity and function of archaea associated with the human body. Using improved methodology, we found that the archaeal diversity is higher than expected, being composed of archaea from several phyla including Euryarchaeota, Thaumarchaeota and Woesearchaeota. We also detected considerable amounts (up to 20%) of archaea on human skin, in gastrointestinal tract, oral cavity and respiratory tract. Additionally, we discovered the body site specific biogeography of human archaeome with predominance of (novel) methanogens in the gastrointestinal tract and unknown, DPANN superphylum-associated archaea in the lung. The function of the archaeal communities present in various human body sites is yet to be uncovered. Of particular interest will be to discover how and when (oxygen sensitive/anaerobic) archaea are acquired during life, how archaea communicate with their hosts or syntrophic partners, and do archaeal pathogens exist.

Session 5: From plants to humans/various topics Thursday 8.11.2018, 16.00-17.20

Plasmid DNA contaminant in molecular reagents Wally N , Schneider M , Thannesberger J , MT Kastner , Bakonyi T , Indik S , Rattei T , J Bedarf , F Hildebrand, J. Law , J Jovel, Steininger C Department of Medicine I, Medical University of Vienna, Vienna, Austria

Background noise in metagenomic studies is often substantial and its removal requires extensive post-analytic, bioinformatics filtering. This is relevant as significant signals may be lost because due to a low signal-to-noise ratio. The presence of plasmid residues, that are frequently present in reagents as contaminants, has not been investigated so far but may pose a substantial bias. Here we show that plasmid sequences from different sources are omnipresent in molecular biology reagents. Using a metagenomic approach, we identified the presence of the (pol) of equine infectious anemia virus in human samples and traced it back to the expression plasmid used for generation of a commercial reverse transcriptase. We found fragments of multiple, other expression plasmids in human samples as well as commercial polymerase preparations. Plasmid contamination sources included production chain of molecular biology reagents as well as contamination of reagents from environment or human handling of samples and reagents. Retrospective analysis of published metagenomic studies revealed an inaccurate signal-to-noise differentiation. Hence, the plasmid sequences that seem to be omnipresent in molecular biology reagents, may misguide conclusions derived from genomic/metagenomics datasets and thus also clinical interpretations. Critical appraisal of metagenomic data sets for the possibility of plasmid background noise is required to identify reliably significant signals.

Is the gut-lung axis bi-directional? Alternations of the gut microbiome in mice with allergic lung disease E. Korb, K. Ambroz, M. Drinic, C. Zwicker, T. Svoboda, M. Ehling-Schulz, B. T. Hanson, C. Herbold, A. Loy, S. Widder , U. Wiedermann, I. Schabussova ISPTM Medical University Vienna, Austria

Host-microbiome interactions play an important role in the development of allergic airway disease. The alternations of the gut microbiota have been linked to the airway inflammation through the gut-lung axis. Here we raised the question, whether this axis is bi-directional. Using mouse models of OVA-specific airway inflammation and orally-induced specific tolerance, we tested the impact of interventions in the lung on the composition and function of the gut microbiota. We employed Fourier transform infrared spectroscopy (FT-IR) and Illumina MiSeq sequencing of 16S rRNA gene amplicons to perform microbial community analysis. Additionally, the metabolic pattern was analyzed by mass spectrometry (MS). FT-IR measurements indicated shifts in the gut microbiome of tolerized and sensitized mice compared to naïve mice. Analysis of 16S rRNA gene sequence data indicated an increase in relative abundances of the families Prevotellaceae and Ruminococcaceae, while Bacteroidaceae were decreased in feces of allergic mice compared to tolerized mice and sham controls. MS revealed a distinct metabolite pattern in serum of sensitized mice, showing a decrease of L-carnitine and its alkylated forms compared to sham controls. Next, we aim to evaluate whether the immune status is transferable via the respective intestinal microbiome to germ-free mice. We show that airway inflammation and induction of tolerance influence the composition of the gut microbiome. The precise characterization of the gut-lung axis, the pathways and mediators might pave the way to the development of novel intervention strategies for respiratory diseases based on commensals.

Changes in the cutaneous microbiome in the course of allogeneic hematopoietic stem cell transplantation Bayer N., Strobl J., Hammerl L.,Riva A., Patra V., Berry D., Stary G Medical University of Vienna, Austria

The success of allogeneic hematopoietic stem cell transplantation (HSCT) remains limited due to severe side-effects, such as infections and graft versus host disease (GVHD). Recent studies suggest that dysbiosis of intestinal microbes is associated with an increased risk of GVHD and poor outcome, while the role of the cutaneous microbiome remains elusive. We obtained patient material (peripheral blood, skin scales, stool and skin biopsies) at 5 time points before myeloablative conditioning and up to one year after HSCT (n=20). The cutaneous and intestinal microbiome is analyzed with 16S rRNA sequencing. In vivo interactions of bacteria with immune cells are monitored by combining monoclonal antibodies with fluorescent in situ hybridization (FISH). Bacterial numbers/mm2 and distance calculations from CD45+ and HLA-DR+ cells are assessed via StrataQuest Software. 16S sequencing was established from healthy stool and skin samples and showed an expected mixture of commensal bacteria. Visualization of bacteria via 16S rRNA-FISH in HSCT patients revealed a decrease in bacteria/mm² skin in the epidermis as well as the upper (<500µm) and lower (>500µm) dermis at day 0 and day 14 after transplantation. At day 100 bacterial numbers were comparable to baseline. Although often in close contact with CD45+cells, no intracellular bacteria were observed. This study gives us the unique possibility to examine the repopulation kinetics and crosstalk between the immune system and the residing microbiome. Furthermore, we will establish risk profiles for GVHD development and occurrence of infections based on the individual skin and gut microbiome.

Increased Staphylococcus aureus abundance in cutaneous squamous cell carcinoma confers microbial growth stimulus for tumor cells Nandhitha Madhusudhan1,2, Manuela-Raluca Pausan3, Bettina Halwachs1,2,8, Jan Kehrmann4, VijayKumar Patra5, Peter Wolf5, Petra Boukamp6, Christine Moissl-Eichinger3,8, Lorenzo Cerroni5, Jürgen C. Becker7*, Gregor Gorkiewicz1,2,8* 1Institute of Pathology, Medical University of Graz, Austria

2Theodor Escherich Laboratory for Medical Microbiome Research, Medical University of Graz, Austria

3Department of Internal Medicine, Medical University of Graz, Austria

4Institute of Medical Microbiology, University Hospital Essen, University of Duisburg-Essen, Germany

5Department of Dermatology, Medical University of Graz, Austria

6Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany

7Department of Translational Skin Cancer Research and Department of Dermatology, German Cancer Consortium (DKTK),

University Hospital Essen, Germany 8BioTechMed-Graz, Graz, Austria

Malignant epithelial skin tumors (e.g. cutaneous squamous cell carcinoma, cSCC) arises from specific precursors (e.g. actinic keratosis, AK). During tumor development the host-microbiota equilibrium is altered and a selected pro-inflammatory cutaneous microbiota might drive cancer progression. Thus to assess the impact of microbiota on skin tumorigenesis, we comparatively assessed the microbial community composition of human skin tumors. These analyses shows that each tumor entity harbors a distinct microbial community type signified by an overabundance of Staphylococcus in AK and SCC and Streptococcus in basal cell carcinoma (BCC). qPCR confirmed these findings and indicated an overabundance of Staphylococcus aureus in SCC. Significantly increased bacterial biomass was found in the hyperkeratotic region of AK & SCC which is absent in BCC indicating that niche alteration in turn alters the concomitant microbiota. Interestingly, AK and SCC showed overexpression of anti-microbial peptides (AMPs) hBD-2 and 3, known to cause hyperproliferation of squamous epithelia. Also, hBD-2 expression was significantly upregulated in cSCC cells when challenged with live S. aureus. Furthermore, hBD-2 significantly promoted the growth of cSCC cells. We, therefore, hypothesize that during neoplasia development, change of the microbial habitat by hyperkeratosis, leads to overgrowth of S. aureus, which in turn promotes growth of tumor cells mediated by hBD-2, thereby perpetuating the neoplastic process.

Antibiotic-associated secondary IgA-deficiency enhances susceptibility to Pseudomonas aeruginosa pneumonia Oliver Robak, Catherine Chaput, Bastian Opitz Medical University of Vienna, Austria

Most patients in intensive care units receive antibiotics, and many develop hospital-acquired infections, with Pseudomonas aeruginosa being a leading cause. Although a preceding antimicrobial therapy is known as a major risk factor for P. aeruginosa-induced pneumonia, the underlying mechanisms remain incompletely understood. Here we demonstrate that antibiotic-mediated microbiota depletion inhibits Toll-like receptor- and APRIL-dependent IgA production in the lung, and that this microbiota-dependent IgA is required for early, pulmonary antibacterial defense in a murine P. aeruginosa pneumonia model. Accordingly, pulmonary APRIL and IgA levels were lower in patients treated with broad-spectrum antibiotics as compared to antibiotic-naïve subjects. Moreover, transnasal application of polyclonal IgA enhanced resistance of antibiotic-treated mice to P. aeruginosa infection. Our study reveals a mechanism potentially explaining the high risk of patients getting antimicrobials to develop pulmonary P. aeruginosa infections, and indicate the prophylactic efficacy of locally administered IgA. Session 6: Microbiota-Modulation Friday 9.11.2018, 9.00-10.30

Microbiome, Molecular Clock and Mood in affective disorders Susanne Bengesser, Eva Reininghaus Medical University of Graz, Austria

Background/Aims: The gut-brain-axis, which is an extensive bidirectional communication network between the gastrointestinal tract and the brain, is in the spotlight of research nowadays. Nevertheless, little is known about the mechanisms of this gut-brain-axis. There are results, which suggest that metabolites of microbiota affect gene regulation in the human body. Thus, we investigated, whether bacterial diversity is interconnected with epigenetic changes in the peripheral blood. Methods: Isolation of genomic DNA with the salting out technique from fasting blood of study participants with BD (n= 32). Methylation analysis of the clock gene ARNTL (CG site cg05733463) was performed with bisulfite treatment/ Epitect kit, PCR and pyrosequencing. The microbiome was analyzed with 16S rRNA sequencing. Results: The methylation status the cg05733463 site of ARNTL correlated significantly with bacterial diversity (Simpson Index: r=-0.389, p=0.0238) and evenness (Simpson evenness index: r=-0.358, p=0.044). Discussion: If the methylation of the clock gene ARNTL was influenced by the gut- i o io e di e sity, p o ioti s ould putati ely ha e a a tidep essa t effe t since the molecular clock is connected with mood regulation (the transcription of the clock gene ARNTL correlates positively with the transcription of the serotonin, noradrenaline and dopamine degrading enzyme MAOA). Probiotics are especially promising for those not benefitting from common antidepressant treatments or for patients suffering from side effects. Nevertheless, further research is necessary.

Immunomodulation of the Human Gut Microbiome via Bacterial Membrane Vesicles Paul Kohl, Franz G. Zingl, Daniel Derndorfer, Christina Passegger, Ba a a Jelušić, G ego Go kie i z, He e t Strobl, Stefan Schild Institute of Molecular Biosciences, University of Graz, Austria

The human gastrointestinal (GI) tract harbours a complex and dynamic microbial community, the gut microbiota. Its immunogenic and metabolic interactions with the host have a crucial impact on gut integrity, homeostasis and host health. Altered gut bacterial composition (dysbiosis) or altered barrier function and translocation of microbial products can lead to chronic inflammation resulting in inflammatory bowel disease (IBD). Furthermore oxidative DNA damage caused by colonic inflammation induces genetic alterations, which can lead to colorectal cancer (CRC). Recent evidence suggests that gut bacteria release membrane vesicles (MVs) from their surface, especially during host colonization. Thus, intestinal epithelial cells are constantly bombarded with these non-living facsimiles of the microbial community. Importantly, MVs contain several immunomodulatory compounds and are there y likely to i pa t the host s i u e syste . The ai of this project is to unravel beneficial or adverse immunomodulatory effects of MVs derived from GI-bacteria in the context of IBD and CRC. Thus we established a pipeline for standardized MV isolation and quality control applicable to a variety of GI-bacteria using filtration and centrifugation steps. Based on a pilot study using Luminex, seven cytokines associated with IBD or CRC and expressed by HT-29 cells upon MV contact have been selected for further analyses. We herein show that MVs derived from individual bacterial species trigger a distinct pro-inflammatory response in intestinal epithelial cells and immune cells. The most promising candidates are currently investigated to identify the bacterial effector molecules and host cell receptors driving this immunomodulation. Session 7: Plant microbiome Friday 9.11.2018, 11.00-13.30

Microbiome and metabolome diversification in medicinal plants Martina Köberl, Richard Allen White III, Albert Rivas-Ubach, Sabine Erschen, Rudolf Bauer, Janet K. Jansson, Christer Jansson, Gabriele Berg Institute of Environmental Biotechnology, Graz University of Technology, Austria

Plants form close interactions with microorganisms that are essential for their performance and survival. Moreover, the plant-associated microbiome influences also the metabolic profile of the plant leading to different metabolic phenotypes, whereby a significant number of metabolites are in fact even produced by associated microbes. To understand the diverse plant-microbiome interactions, detailed insights are necessary in order to uncover targeted directions for plant metabotype improvements. Multiphasic approaches combining different omics technologies were exploited to investigate medicinal plants (Matricaria

chamomilla, Calendula officinalis, Solanum distichum) under field and controlled conditions. Microbiome analyses revealed a plant-specific microbial colonization of the rhizosphere and phyllosphere, while the endophytic niche showed a more similar microbiome composition characterized by a subset of species and a significantly lower diversity. The rhizosphere communities of all investigated medicinal plants unveiled an outstandingly high microbial diversity, most notable in comparison to crop plants grown in intense agriculture. Metagenomic binning enabled the reconstruction of >100 rhizobacterial genome bins, including five nearly complete draft genomes. The ectophytic phyllosphere microbiome of the Asteraceae medicinal plants was dominated by Proteobacteria, Firmicutes and Actinobacteria, while the leaf endospheres were almost exclusively inhabited by Proteobacteria. The flower metabolomes of the Asteraceae medicinal plants revealed a striking complexity and were highly specific for the different plant species but also for the individual sampling sites (Austria, WA/USA, Egypt). Several individual metabolites with significant differences between samples from different sites and plant species could be identified, among them also bioactive compounds, such as the phytotherapeutic flavonoids apigenin, luteolin and quercetin.

Three are better than one - in silico, in vivo and in vitro analysis of the antibiotic resistome of a moss microbiome Melanie-Maria Obermeier, Julian Taffner, Christina Andrea Müller, Gabriele Berg Graz University of Technology, Austria

The antibiotic resistance crisis urges the development of novel therapeutics. A promising bio-resource for the identification of novel drug leads are the microorganisms associated with Sphagnum magellanicum mosses. This highly specific and unique microbiota is known to harbour a high proportion of antimicrobial functions. To investigate this potential in more depth we explored the antibiotic resistome using, first-time, a three-dimensional approach consisting of in silico, in vivo and in vitro screenings. In silico, the S. magellanicum metagenome was screened for antibiotic resistance genes by performing a BLAST search against the Comprehensive Antibiotic Resistance Database with a cut-off of 90% similarity. 666 antibiotic resistance genes targeting 21 drug classes were assigned including synthetic antibioti s. Most hits e e assig ed to β-lactamases and glycopeptides. Ten antibiotics from eight of the detected drug classes were used for further testing. Bacterial isolates (in vivo) and a metagenomic library (in vitro) were screened for antibiotic resistances. Thereby, 50% of all isolates showed resistance against ampicillin, sulfadiazine and vancomycin with the majority of the isolates growing on at least one of the tested antibiotics. For the metagenomic library solely clones resistant against ampicillin were identified. Whole-insert sequencing and gene annotation for one such clone revealed a novel β-lactamase. Based on its homology and substrate specificity, the identified β-lactamase classifies as carbenicillinase. While each of the used methods highlights the prevalence of β-lactamases within the studied microbiome, the multiple analyses compensated the short comings of each method and resulted in a more holistic understanding of the antibiotic resistome.

Naturally occurring antibiotic resistances in the microbiome of leafy greens Tomislav Cernava, Armin Erlacher, and Gabriele Berg Graz University of Technology, Austria

Eruca vesicaria var. sativa (Mill.) Thell., commonly known as arugula, is a popular raw-eaten ingredient in salads due to its peppery, pungent taste. Similar to other leafy greens, E. sativa is colonized by a vast diversity of microbes, hi h o ple e t the holo io t s fu tio i g. The i dige ous i o iota o ly a ely allo s foodborne pathogens to settle, indicating high competitiveness. Nevertheless, the prevalence of resistances in such microbial communities is only poorly understood. We analyzed the structure, abundance and functioning of the plant-associated microbiota in the arugula phyllosphere, rhizosphere and the corresponding bulk soil in an integrative approach. When compared to the rhizosphere, higher proportions of Gammaproteobacteria, including Enterobacteriaceae were observed in aerial plant parts. Their occurrence was verified by fluorescence in situ hybridization coupled with confocal laser scanning microcopy in different plant compartments. Complementary metagenomic profiling of the bacterial population indicated a higher prevalence of antibiotic resistances in plant-derived samples. We found general resistance mechanisms including various efflux pumps in the datasets, but also specific resistance mechanisms against fluoroquinolone, chloramphenicol and other antibiotics. Due to the high occurrence of Enterobacteriaceae in arugula samples, we screened a representative culture collection for resistances against eight common antibiotics. It was shown that more than 90% of the isolates were resistant against Ampicillin, Erythromycin, and Penicillin. Our findings suggest that antibiotic resistance is common in distinct raw-eaten plants; however, the implications for human health remain unclear.

Endophytic bacteria as promising biotechnological resource for biocontrol of phytopathogens Vladimir CHEBOTAR, Andrey SHCHERBAKOV, Elena SHCHERBAKOVA, Egor VOINOV, Alexander ZAPLATKIN, Natalia MALFANOVA Russia Research Institute for Agricultural Microbiology, Saint-Petersburg, Russia

Microbiome of seeds and vegetative parts of conifers (Norway spruce, Scots pine, European larch) plants has been studied. It is shown that at the level of phila dominated by the representatives of Proteobacteria and Actinobacteria. The most interesting results of microbiome analysis of coniferous plants seeds was obtained at the level of families. For Norway spruce found that the diversity of endophytic bacteria in the composition of the microbiome is small and is determined by two main families: Enterobacteriaceae, and Comamonadaceae, which presented in the composition of the microbiome of the seeds from the Republic of Tatarstan and the Republic of Mari El. Analysis of species diversity of bacteria in the microbiome composition of the vegetative parts of conifers showed similarity to the microbiomes of endosphere of seeds of conifers. It is shown that the composition of the endophytic microbiome of the vegetative parts of conifers found not more than 2-3 species of bacteria that belong to the same families that were found in the seeds. To study the sites of colonization of endophytic bacteria in the internal tissues of plants labelled strain of Pseudomonas sp. 2ES+dsRED has been designed. It was studied the spatial localization of endophytic microorganisms in plants using fluorescence in situ hybridization (FISH) and with the help of dsRED -labeled strain. It was established that the cells of the bacteria Bacillus atrophaeus 14 actively settled endosperm of wheat, lying in its conductive tissues. Cells of bacteria Pseudomonas sp. 2ES+dsRED were localized in the porous vessels of the shoots of grapes, lying single or in small clusters. Their ability to the circulation through the vessels of plants of grapes has been observed. In model experiments it was shown that endophytic bacteria are able to colonize the root surfaces and the rhizosphere of plants. In pot and field experiments the effectiveness of endophytic bacteria on grapes, oats and radishes was demonstrated. Thus, the increase in root length of plants oat radish increased by 43-100% in comparison with the control, and the grape harvest increased by 7.7%. As a result of experiment with the transgenic line DR5-GUS of Arabidopsis thaliana changes in the amount and localization of auxin under the influence of metabolites in culture medium of bacteria were identified. The increase and change in localization of expression of DR5-GUS was observed under the action of metabolites of strains of Bacillus subtilis 6ES and Pseudomonas asplenii RMBD. Under the influence of metabolites of the standard strain B. subtilis Ch-13 small increase in the expression of DR5-GUS was detected only in the transition zone between the meristem and the zone of tension. In a solution of IAA at a concentration of 10-7M (0.17 µg/ml) increase of GUS expression was strongest. Thus, on the basis of obtained data we can conclude that not all indole compounds identified in culture medium of strains are biologically active auxins.

ABSTRACTS | POSTERS Poster 1-1 Pathobiont Klebsiella oxytoca produces the genotoxic metabolite tilimycin in human and mouse intestine Kitsera, M1, Unterhauser, K1, Pöltl, L1, Pletz, J1, Glabonjat, R.A.1, Lembacher-Fadum, C2, Dornisch, E1, Gorkiewicz, G3, Högenauer, C3, Breinbauer, R2, Schild, S1 and Zechner, E.L.1 1University of Graz, BioTechMed-Graz, Graz, Austria

2Technical University of Graz, Graz, Austria

3Medical University of Graz, Graz, Austria

K. oxytoca is a pathobiont of the human intestinal microbiota that is carried by 3-10% of healthy individuals [1]. In some patients taking antibiotics, the bacterium causes antibiotic-associated hemorrhagic colitis. Disease was linked to the bacterial secondary metabolites tilivalline (TV) and tilimycin (TM) [2, 3]. Both enterotoxins belong to the pyrrolobenzodiazepines. The structure of TM suggests it may interact with DNA. In this study we determined the molecular targets of the toxins and effects on human cells. We verified that both cytotoxins are present in the colon and feces of infected patients and mice. In vitro each toxin disrupts cell cycle progression: TV arrests cells in G2/M and TM at G1/S phase. The hypothesis that TM damages DNA was tested using nuclease assays and Comet assays of DNA fragmentation in human epithelial cells in vitro. Genome instability was observed in cecum of mice colonized with wild-type K. oxytoca but not toxin-deficient mutants. Cellular exposure to both substances causes apoptosis in vitro and in vivo. This study provides clear mechanistic understanding of K. oxytoca s a ility to ause a ti ioti -induced colitis and raises the important question of whether lifetime carriage of K. oxytoca poses an increased risk for initiation or progression of CRC. [1] Hoegenauer, C., et al. Klebsiella oxytoca as a causative organism of antibiotic associated hemorrhagic colitis. N Engl J Med. 355(23):2418-2426 (2006). [2] Schneditz, G., et al. Enterotoxicity of a nonribosomal peptide causes antibiotic associated colitis. PNAS. 111(36):13181-13186 (2014). [3] Dornisch, E., et al. Biosynthesis of the enterotoxic pyrrolobenzodiazepine natural product tilivalline. Angew Chem Int Ed Engl. 56(46):14753-14757 (2017).

Poster 1-2 The role of diet-i du ed β-glucuronidase activity of gut microbiota in estrogen bioavailability Mihajlovic Jovana, Stanic Irena, Herbold Craig, Aichinger Georg, Preindl Karin, Spittler Andreas, Marko Doris, Warth Benedikt, Wisgrill Lukas, Berry David Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network Chemistry Meets

Microbiology, University of Vienna, Vienna, Austria

Functional studies in mice, together with clinical studies on colorectal cancer patients suggest that estrogen contributes to maintenance of intestinal homeostasis by suppressing inflammation. A potentially important source of estrogen in the gut might be the systemic estrogen that are excreted via the gastrointestinal tract in the form of glucuronic acid conjugates that could be a potential substrate for bacterial ß-glucuronidases. By e o i g the glu u o i a id, β-glucuronidases can restore bioactivity of glucuronide-conjugated metabolites,

i ludi g est oge . This ea ti atio effe t ediated y a te ial β-glucuronidases might affect bioavailability of steroid hormones in the gut and have yet unconsidered implications to intestinal physiology. In the present study we examine how diet- egulated β-glucuronidase activity affects the capacity of gut microbiota to deconjugate 17-β-estradiol-glucuronide. We first showed that incubation of human fecal matter with diverse carbon sources results in different induction of glucuronidase activity. In order to examine diet-dependent capacity of gut bacteria to deconjugate estrogen-glucuronide, we exposed stool samples undergone incubation with different dietary compounds to 17-β-estradiol-glucuronide and we are currently estimating the amount of released 17-β-estradiol using chemical analysis and estrogenicity assays in cell culture. Additionally, we were able to target the ß-glucuronidase producers using click-chemistry fluorescent labeling and we are currently working towards identifying them through FACS sorting followed by 16s rRNA gene amplicon sequencing. We expect the resulting data to point to the main producers of ß-glucuronidases in human gut microbiota and provide insight into how diet-i du ed β-glucuronidase activity might affect host physiology.

Poster 1-3 Associations between gut microbiota and social behavior: Insights from a cohort of captive common marmosets (Callithrix jacchus) Huimin Ye, Vedrana Slipogor, Buck T. Hanson, Thomas Bugnyar, Alexander Loy Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, Research Network Chemistry meets

Microbiology, University of Vienna, Vienna, Austria

Previous studies showed that cohabitants share similar gut microbiota. However, how individual interactions influence the microbiota amongst cohabitants is still unknown. Common marmosets are highly social animals and share many similarities with humans including family structure, intestinal anatomy, and basic diet. Therefore, captive common marmosets are used as a non-human model to test hypotheses that the frequency and intensity of certain social interactions, such as grooming, sharing food, and playing, can lead to differences in the gut microbiota between family groups. Marmosets were housed in two adjacent rooms having three and four distinct family units. All monkeys were fed controlled diets and examined for 8 weeks. Feces were sampled twice weekly, from which DNA was extracted for 16S rRNA and dsrB (marker gene for sulfite-reducing bacteria) gene amplicon sequencing. Concentrations of fecal short-chain fatty acids were measured and social behaviors were recorded by video filming. Analysis of dsrB gene amplicons revealed the presence of Bilophila sp. and Desulfovibrio spp. (1 & 3 OTUs, respectively). 16S rRNA sequencing results showed that the marmoset gut microbiota is predominated by Bacteroidetes, Firmicutes, Actinobacteria and Proteobacteria. Similarity analysis revealed that the gut microbial compositions of family members are more similar to each other compared with non-family members (P < 0.05). In addition, there are no significant associations between gut microbiota and ages or body weight, suggesting the interactions between family members might be a main factor influence the microbial similarity of family members. The associations of gut microbiota and behaviors will be examined.

Poster 1-4 Changes in the intestinal microbiome during a multispecies probiotic intervention in compensated cirrhosis Angela Horvath, Marija Durdevic, Bettina Leber, Katharina G. di Vora, Florian Rainer, Philipp Douschan, Elisabeth Krones, Walter Spindelboeck, Franziska Durchschein, Gernot Zollner, Rudolf E. Stauber, Peter Fickert, Philipp Stiegler, Vanessa Stadlbauer Department of Gastroenterology and Hepatology, Medical University of Graz, Austria

Liver cirrhosis is accompanied by significant changes of the intestinal microbiome including the regression of beneficial and autochthonous taxa. The aim of the study was to test the effects of a multispecies probiotic on gut i o io e o positio . Gut i o io e o positio of 8 patie ts ith Child s A i hosis ho received a daily dose (1.5*1010 CFU) of a multispecies probiotic or placebo for six months was analysed by 16S rRNA gene sequencing. Microbiome composition of patients was enriched with probiotic strains Lactobacillus salivarius, Lactobacillus brevis and Lactococcus lactis. Furthermore, the abundance of short-chain fatty acid producing bacteria Faecalibacterium prausnitzii, Syntrophococcus sucromutans and Alistipes shahii was increased in the probiotic group compared to the placebo group. Changes in starch-utilizing bacteria of the species Bacteriodes vulgatus could be observed in both groups. A six months intervention with a multispecies probiotic enriched the microbiome of cirrhotic patients with probiotic bacteria. The abundance of anaerobic and short-chain fatty acid producing bacteria was increased in patients in the probiotic group and changes in starch-utilizing bacteria were observed in both groups.

Poster 1-5 Differences of the luminal and mucosa-associated microbiome along the gastrointestinal tract: a study in mice and surgically treated neonates Georg Singer, Christoph Castellani, Ingeborg Klymiuk, Slave Trajanoski, Beate Obermüller, Holger Till Department of Paediatric and Adolescent Surgery, Medical University of Graz, Graz, Austria

The intestinal microbiome, harboring the entity of bacterial, fungal, viral and archaeal microorganisms colonizing our intestine is of major importance for many aspects in human health and disease. Differential microbial pattern and quantity have been found along the gastrointestinal tract. The aims of this study were 1) to describe differences between the mucosa associated (resident) and luminal (transient) microbiome along the gastrointestinal tract in mice and 2) to assess these differences also in the gastrointestinal tract in surgically treated pediatric patients. The luminal and mucosal microbiome was measured with 16S rRNA sequencing in nine female mice (B6CBAF2)) along the gastrointestinal tract (jejunum, ileum, colon). Additionally, the luminal and mucosal intestinal microbiome was assessed in five infants treated with enterostomies at the time of closure of the stomata. The most dominant taxa were similar between colon region and stool samples (Lachnospiraceae, Enterobacteriaceae, Verrucomicrobiaceae. Taxa and relative abundances differed mainly compared to Jejunum (Lachnospiraceae, Enterobacteriaceae, Peptostreptococcaceae) and Ileum (dominated by Peptostreptococcaceae followed by Lachnospiraceae and Enterobacteriaceae) region. Differences between mucosa and lumen derived samples could be found in the Chao1 index calculation with a trend to a lower estimated diversity in mucosa derived samples as well as in the relative abundance of individual taxa. Additionally, in this study we have examined the difference between mucosal and luminal bacterial colonization in a small neonate sample cohort for the first time. Individual differences are characterized (e.g. Clostridium sensu stricto, Streptococcus) but did not reach statistically significance due to the small sample cohort.

Poster 1-6 The correspondence of the nasal microbiome and olfactory function – or: The nose-brain axis Christina Kumpitsch1, Kaisa Koskinen1,2, Florian Ph.S Fischmeister3, Christine Moissl-Eichinger1,2, Veronika Schöpf2,3 1 Internal Medicine, Medical University of Graz, Austria

2 BioTechMed-Graz, Austria

3 Institute of Psychology, University of Graz, Austria

20% of the general population suffers from olfactory dysfunction; almost 5% from a complete loss of olfaction. This loss is either caused by infection, mechanical impact, or subtly during the process of ageing. No matter which cause, most of them report tremendous effects on the quality of life due to impairments of psychological, social, and behavioral performance, as olfactory dysfunction can induce reorganization of the human brain. Our sense of smell is mediate by olfactory sensory neurons. These neurons are located in the ceiling of the nose, the olfactory area. Like all surface areas of the human body, also this area is inhabited by numerous microorganisms. It is well known that this microbiome is capable to communicate with the human body cells and thus affects functions of human tissues and even brain. This project aims to decipher the role of the human nasal microbiome in connection with olfactory function, dysfunction, and regain. Neuroimaging biomarkers and olfactory function were correlated with microbiome measurements such as diversity and abundance. Furthermore, cultivation experiments, interaction assays, and metabolomics will be performed, as well as scanning electron microscopy. Our completed pilot study has shown that the microbial community composition in the olfactory mucosa mirrors the capability to smell. Participants with impaired olfactory performance showed an increase of specific (anaerobic) microbial groups, such as butyrate producing microorganisms. This knowledge of the microbial community of the olfactory mucosa increases therapeutic opportunities, and possibly allows monitoring and predicting smell therapy success in future.

Poster 1-7 I pa t of the fi st do ai of life - improved protocols for detection and quantification of archaeal signatures from the human microbiome Marcus Blohs1, Manuela Pausan1, Kaisa Koskinen1,2, Christoph Högenauer1, Ruth Schmitz-Streit3, Christine Moissl-Eichinger1,2 1 Medical University of Graz, Austria,

2 BioTechMed-Graz, Austria

3 University of Kiel, Germany

Humans are host to a high variety of microorganisms, including archaea, bacteria, eukaryotes, and viruses. During the last decades it became apparent that the interplay between host and its microbiome is crucial and influences the host health and well-being. While the role of bacteria is extensively studied to date, we know athe little a out fu tio a d di e sity of the othe do ai s. This i ludes also the fi st do ai of life if

arranged alphabetically): archaea, even though they can account for up to 50% of microbial species in certain body parts such as the appendix. Their underrepresentation in microbiome studies is reasoned by several methodological pitfalls, so that the archaeal presence, abundance and importance are largely underestimated. Here, we propose improved, archaea-specific primers for 16S rRNA gene detection and quantification, as well as new approaches for isolation and cultivation of methanogenic archaea from the gut. Our protocols will help to reveal the important roles of Archaea in the body-microbiome interplay and their clinical relevance.

Poster 1-8 In-vitro fermentation of a medicinal plant extract by human faeces to investigate its metabolization and the shift in the microbiome composition Thumann T.1,2, Pferschy-Wenzig E.M.1,2, Moissl-Eichinger C.2,3, Aziz-Kalbhenn H.4, Rabini S.4, Bauer R.1,2; 1 Institute of Pharmaceutical Sciences, Department of Pharmacognosy, University of Graz, Austria

2 BioTechMed-Graz, Austria

3 Medical University of Graz, Austria

4 Steigerwald Arzneimittelwerk GmbH, Bayer Consumer Health, Darmstadt, Germany

Introduction The herbal preparation STW-5 consists of the following nine plant extracts: bitter candytuft whole plants, greater celandine herbs, angelica roots, lemon balm leaves, peppermint leaves, caraway fruits, liquorice roots, chamomile flowers and milk thistle fruits. It is used against functional dyspepsia and irritable bowel syndrome (IBS) [1]. The aim of the present study was to assess the impact of gastrointestinal digestion on the chemical composition and the interaction with human gut microbiota in-vitro. Method First, the herbal preparation was digested by a static in-vitro digestion method called InfoGest [2] to simulate the conditions in the gastric and small intestinal phase. Second, the incubate of the intestinal phase was mixed with human fecal samples under anaerobic conditions to mimic the microbial fermentation in the gut. Samples were taken after 30 min, 4 h and 24 h of incubation. Changes in the metabolic profile of the preparation were assessed by UHPLC-HRMS metabolomics, and microbiome changes were investigated by Illumina Next Generation Sequencing. Results A shift in the microbial community composition caused by STW-5 addition could be detected. The metabolization of the main STW5 constituents such as flavonoids and triterpene glycosides by the fecal microbiota led to formation of new small molecule metabolites.

Poster 1-9 Does the gut microbiome affect intestinal steroidogenesis? Michaela Krainer, Judith Gumhold, Dagmar Silbert-Wagner, Silvia Racedo, Kathrin Panzitt, Martin Wagner Department of Internal Medicine, Research Unit for Translational Nuclear Receptor Research, Division of Gastroenterology

and Hepatology, Medical University of Graz, Austria

Introduction: The intestine is a source for locally active glucocorticoid generation. Although intestinal ste oidoge esis does t o t i ute to syste i le els, lo ally p odu ed glu o o ti oids ay e ele a t fo the maintenance of intestinal immune homeostasis and epithelial barrier as well as the regulation of inflammatory processes. Several indirect links suggest that the gut microbiome might affect local steroidogenesis, which could be clinically relevant. First, steroidogenic enzymes in the intestine are regulated by the nuclear receptor (NR) and transcription factor LRH-1. Both, steroidogenic enzymes as well as the regulating NR LRH-1 are reduced in inflamed parts of the colon of patients with inflammatory bowel disease (IBD). Second, steroid treatment is standard of care in the treatment of patients with IBD and fecal microbiota transplantation is a promising experimental therapeutic option for IBD patients with ulcerative colitis. We therefore hypothesize, that the gut microbiome affects (enzyme expression of) local steroidogenesis and speculate that this is mediated via LRH-1 signaling. Methods: To determine the effect of the microbiome on intestinal steroidogenesis, we compared different parts of the intestine (jejunum, ileum and colon) of germfree and conventional mice (n=5 each). We focused on the key steroidogenic enzymes Cyp11a1, Hsd3b and Cyp11b1, which are all regulated by LRH-1. To test expression levels, we performed RT-qPCR, Western Blotting (WB) and immunofluorescence (IF) staining. Results: Lrh-1 was expressed along all parts of the intestine and there was no difference between conventional and germfree mice. There was significant difference in the expression levels of steroidogenic enzymes, which depended on localization but also on the presence or absence of the gut microbiome. The differences were most pronounced on protein levels for Cyp11b1, which was robustly expressed to equal levels in colon and ileum, but significantly lower expressed in germfree mice. Cyp11a1 was only expressed in the colon but not significantly changed between germfree and conventional mice. On mRNA levels the most robust differences between germfree and conventional mice were detected for Hsd3b1 and 3, which were expressed significantly less in the colon of germfree mice contrary to increased expression in the ileum. Discussion/conclusion: The presence of a gut microbiome significantly affects steroidogenic enzyme expression in the intestine. The differences are most evident for Cyp11b1, which is significantly less expressed in germfree mice. The role of LRH-1 in mediating these effects is currently not clear and further in-depth analysis (e.g. LRH-1 chromatin immunoprecipitations) is required. Future studies will determine the expression levels in patients before and after FMT to translate the rodent findings into a clinically relevant background in human patients.

Poster 1-10 Akkermansia muciniphila in fecal microbiota transplantation Barbara Jelušić 1, Philipp Wurm1, Paul Kohl2, Stefan Schild2,4, Patrizia Kump3, Christoph Högenauer3, Christina Angelika Passegger5, Herbert Strobl5, Gregor Gorkiewicz1 1Institute of Pathology, Medical University of Graz, Austria

2Institute of Molecular Biosciences, University of Graz, Austria

3Division of Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Austria

4BioTechMed-Graz, Austria

5Pathophysiology & Immunology, Medical University of Graz, Austria

Fecal microbiota transplantation (FMT) is a promising therapy for inflammatory bowel diseases (IBD), including ulcerative colitis. The procedure comprises a healthy individual who donates stool to be transplanted to the intestinal tract of the recipient. Previously, we conducted a trial of repeated FMT in patients suffering from active ulcerative colitis and not responding to conventional therapy. 10 out of 17 patients showed a clinical response. 16S rRNA gene-based microbiota analysis revealed higher relative abundance of several bacterial taxa in donor stool associated with remission. A prominent finding was the species Akkermansia muciniphila. To better understand its association with successful FMTs, we are performing follow-up studies on interactions of A. muciniphila with intestinal environment. Communication between microbiota and the host can be initiated by not only bacterial cells, but also bacterial outer membrane vesicles (OMVs). The small vesicles carry specific cargo to host cells, potentially modulating the immune response. We isolated OMVs from A. muciniphila and Fusobacterium nucleatum, a pathobiont associated with IBD and colorectal cancer. OMVs from both species upregulate inflammatory cytokines in macrophages, with A. muciniphila showing weaker upregulation. Before bacteria and their OMVs can reach the immune cells, they encounter the epithelial layer. We hypothesize that A. muciniphila can induce production of mucin by a human epithelial cell line without exhibiting a strong inflammatory effect, as opposed to F. nucleatum. Investigating direct effects of A. muciniphila on the constituents of human colon will provide insight into its role in FMT, but also into mechanisms of a possible mutualism.

Poster 1-11 Virome dynamics in lung transplant recipients that develop a human cytomegalovirus infection Maia Segura-Wang and Elisabeth Puchhammer-Stöckl Medical University of Vienna / Center for Virology, Vienna, Austria

Human Cytomegalovirus (HCMV) is a major cause of morbidity and mortality in immunosuppressed patients, like lung transplant recipients (LTRs). Little is known about the dynamics of viral populations and their relation to HCMV infection after lung transplantation. We used metagenomic sequencing to characterize the viromes of LTRs with and without HCMV infection. For 10 LTRs that developed a HCMV infection, 3 bronchoalveolar lavage (BAL) samples were sequenced: 2 during the first 100 days post transplantation and 1 at the first time of HCMV load >1000 copies. Control LTRs that did not develop HCMV infection were also analyzed. The diversity and relative composition of viral strains was assessed for each patient and compared to the control samples. The most abundant viral family detected in patients and controls was Anelloviridae. Other families were found only in few patients or time points. The anellovirus abundance increased significantly (Wilcoxon rank sum test, p<0.05) at the second time point (around the time of the end of immunosuppression) in the patients with HCMV infection. The abundance and the number of anellovirus strains were significantly higher in LTRs that developed HCMV (Wilcoxon rank sum test, p<0.05). Differentially abundant strains between the patients and controls were identified, all with a higher abundance in the LTRs with HCMV infection. Our analyses revealed a broad spectrum of virus strains, especially anelloviruses, present specifically in LTRs that develop HCMV infection compared to those that did not. Some specific anellovirus strains might be related to the development of HCMV infections.

Poster 1-12 Helicobacter pylori manipulates the NKG2D tumour surveillance system Margit Neger, Sebastian Wrighton, Ana Montalban-Arques, Philipp Wurm, Silvia Schauer, Markus Windisch, Gernot Posselt, Gregor Gorkiewicz Medical University of Graz, Austria

The Eplsilon-P oteo a te iu Heli o a te pylo i olo izes the sto a h of half of the o ld s populatio a d usually persists for a lifetime. The bacterium is considered a pathobiont – it is a major risk factor for developing gastritis, ulcers and gastric malignancies but it is also associated with protection from immunologic disorders like asthma and allergies. This two-sided effect may be explained y H. pylo i s i pa t o the immune system. H. pylori infection causes a strong immune infiltration of the gastric mucosa, however, bacterial pathogenicity factors impair immune activation to subvert eradication of H. pylori. In this context we observed a down regulation of the NKG2D stress- and tumour surveillance system in H. pylori carriers (Montalban-Arques et al., 2016). Under conditions of stress, infection or tumour transformation epithelial cells express ligands for the receptor NKG2D typically expressed by NK- and CD8+ T cells. Binding of the receptor to its ligands results in the cytolysis of the ligand-expressing cells. We hypothesize that H. pylori modulates the NKG2D system to establish a tolerogenic immune milieu that allows bacterial persistence but might also impair tumour recognition thus contributing to gastric carcinogenesis. Immunohistochemical studies of NKG2D ligands in gastric biopsies revealed altered expression patterns in infected patients. Staining suggested a release of soluble ligands from the epithelial cells. In vitro infection assays using gastric epithelial cell lines confirmed the release of soluble ligands from infected cells and additionally demonstrated a role of the H. pylori vacuolating toxin VacA in this process. Soluble NKG2D ligands are known to act as repressors of the NKG2D receptor. In conclusion we show that H. pylori initiates an immune evasion strategy which might contribute to chronic infection and its sequels like stomach cancer.

Poster 1-13 Supplementation of L-citrulline attenuates the progression of non-alcoholic fatty liver disease (NAFLD) D. Rajcic1, C. Sellmann2, A.M. Hernández-Arriaga3, A. Baumann1, A. Brandt1, A. Nier1, C.J. Jin2, F. Jung1, A. Camarinha-Silva3, I. Bergheim1 1Department of Nutritional Sciences, University of Vienna, Vienna, Austria

2Institute of Nutrition, Friedrich-Schiller-University Jena, Jena, Germany

3Institute of Animal Science, University of Hohenheim, Stuttgart, Germany

Results of several studies suggest that orally supplemented L-citrulline (Cit) may have beneficial effects on the development of liver diseases including non-alcoholic fatty liver disease (NAFLD). Our aim was to assess if Cit attenuates the diet-induced NAFLD progression in mice and to identify mechanism involved. C57BL/6J mice were either fed a liquid fat-, fructose- and cholesterol-rich diet (FFC) or control diet (C) for 8 weeks to induce early stages of NAFLD (e.g. steatosis) followed by a treatment phase of pair-feeding animals C or FFC +/-2.5g L-Cit/kg BW for 5 more weeks, or a FFC or C supplemented with or without 2.5g/kg Cit, +/-0.01g/kg nor-NOHA i.p. for 8 weeks. Indices of liver damage, inflammation and intestinal barrier function were determined. Arginase activity and microbiota composition were analyzed in small intestine. FFC+Cit-fed mice developed significantly lower hepatic inflammation than FFC-fed mice being associated with significantly lower bacterial endotoxin level in portal plasma and a protection against the loss of tight junction proteins in proximal small intestine. While intestinal microbiota composition in small intestine was altered in all FFC-fed animals, beneficial effect of Cit-supplementation seemed to result from a normalization of arginase activity in small intestine. Indeed, treatment with the arginase inhibitor nor-NOHA abolished the effects of Cit on intestinal barrier function and the development of NAFLD. Conclusions: Our results suggest that the protective effects of Cit on the development and progression of NAFLD are related to alterations of intestinal arginase activity.

Poster 1-14 Recipient-Donor signature in predicting clinical response of Faecal Microbiota Transplantation M. Durdevic1,2, P. Wurm1,3, P. Kump3,4, C. Högenauer3,4, G. Gorkiewicz1,3,5 1 Institute of Pathology, Medical University of Graz, Austria

2 Center for Medical Research, Medical University of Graz, Austria

3 Theodor Escherich Laboratory for Medical Microbiome Research, Medical University of Graz, Graz, Austria.

4 Division of

Gastroenterology and Hepatology, Department of Internal Medicine, Medical University of Graz, Austria 5 BioTechMed-Graz, Austria

The introduction of FMT into clinical practice opened up a new therapeutic avenue for the treatment of patients with gastrointestinal inflammatory diseases, like IBD. Although data suggest that donor microbiota has a major role in influencing the efficacy of FMT, individual FMT studies often provide inconsistent results. Moreover, efficacy of FMT appears to be influenced not only by donor factors, like the taxonomic composition, but also by recipient factors beyond microbial composition like inflammatory burden. Thus a more complex approach for FMT data analysis is necessary to understand its biological foundations. Microbiome data analysis poses great statistical and computational challenges, including normalization and quantification issues of the data. Moreover, the multi-faceted data structure (including metadata) makes the application of a more complex analysis approach necessary. To that end machine learning is an ideal approach to deal with huge data sets wherein the underlying model and structure of the data is unknown. In our project we emphasize linear modelling and transformation to address normalization issues in order to remove technical noise and simultaneously preserve biological variations in FMT data sets. Furthermore, employing powerful machine learning methods we seek to rapidly infer discriminating characteristics and determine recipient and donor key microbiota compositions associated with FMT efficacy. Our approach can provide a new understanding on how donor microbiota interact with recipient microbial communities and may be of great practical value in developing personalized probiotic products with defined bacterial populations.

Poster 1-15 First insights into the potential ecology of skin-associated archaea Daniela Brunner, Alexander Mahnert, Kaisa Koskinen, Vijaykumar Patra, Peter Wolf, Christa Schleper and Christine Moissl-Eichinger Department of Internal Medicine, Medical University of Graz, Austria

Human-associated archaea are still overlooked and not specifically targeted elements of the human microbiome. However, our recent study revealed the unique biogeographic pattern of archaea in and on the human body by optimized methodological procedures. While the gastrointestinal tract is dominated by methanogens, the landscape of the skin revealed high abundances (up to 10%) of Thaumarchaeota, as shown by quantitative PCR and fluorescence in situ hybridization. These Thaumarchaeota seem to follow a triphasic distribution during the entire lifespan on human skin with higher prevalence and diversity in childhood and elder hood than on middle-aged subjects. Based on FTIR-FPA hyperspectral imaging and quantitative PCR we hypothesized that lower sebum contents might support the presence of these archaea. Furthermore, due to the successful detection of thaumarchaeal amoA genes in human skin samples, these thaumarchaeota might be involved in ammonia-oxidation and nitrification. Since this metabolism could decrease the pH, a positive effect on human skin and its prime function as a barrier and first line of defense could be considered. In an ongoing study we will screen different age groups longitudinally and investigate thaumarchaeal correlations with typical skin diseases like atopic dermatitis and psoriasis by 16S rRNA gene profiling. These methods will help us to better understand the ecology of archaea on the human body and their possible involvement in health and disease.

Poster 1-16 Connection between cardioautonomic indices and gut microbiota diversity in women Andreas Oberascher, Sabrina Mörkl, Sonja Lackner, Maximilian Moser, Sandra Johanna Holasek Department of Psychiatry and psychotherapeutic Medicine, Graz, Austria

Introduction: Vagal activity has been linked to the control of inflammation and the gut microbiota, connecting the gut and the brain through the gut-brain-axis. Vagal tone can be continuously and non-invasively measured through the high frequency respiratory components of heart rate variability called respiratory sinus arrhythmia (RSA). The aim of this study was to evaluate possible interactions of the autonomic nervous system and gut microbiome diversity. Methods: Beat to beat heart rate variability was recorded with ambulatory high-precision solid state recorders (ChronoCord, joysys, Weiz, Austria) in 73 female study participants (mean age 24.45(SD 4.34); mean BMI 24.27(SD 6.01)). DNA was extracted from stool and subjected to 16S rRNA gene analysis. QIIME was used to analyze gut microbiome data. Results: All three gut microbiota diversity indices (Chao-1-diversity, number of observed species, Shannon-index) showed significant positive correlations with normalized vagal tone(logRSA, p<0.01) and the mean normalized component of total heart rate variability during wake state(lnTOTwake, p<0.01). Chao-1-Diversity showed positive correlations with the standard deviation of all normal R-R intervals(SDNN, p<0.05) and the mean normalized low frequency (LF) and high frequency (HF) component(lnLF/lnHF, p<0.05) and the pulse-respiration-quotient(Qpr, p<0.05). Pearsons correlations identified SDNNsleep%(r=0.235, p<0.05), logRSAwake%(r=0.273, p<0.05),lnTOTwake%(r= 0.275, p<0.05) to correlate with Shannon Diversity Index. Conclusions: This study highlights the important interactions of the gut and the brain via the vagal nerve. More longitudinal, interventional studies are needed to elucidate the mechanisms of the gut-brain-axis in the context of microbial diversity, the vagal tone and effects on inflammation, food choices, satiety and body composition.

Poster 1-17 Skin microbiome modulates the effect of UV on cellular response and immune function VijayKumar Patra, Karin Wagner, Velmurugesan Arulampalam, Peter Wolf Department of Dermatology, Medical University of Graz, Austria

The skin is colonized by a diverse microbiome intricately involved in various molecular and cellular processes within the skin and beyond. Ultraviolet radiation is known to induce profound changes in the skin and modulate immune response. However, the role of the skin microbiome in UV-induced immune suppression has been overlooked. We addressed the question of microbial involvement in UV-induced immune suppression by using the standard model of contact hypersensitivity in the presence or absence of the microbiome (in germ free [GF] and disinfected mice) and found that the microbiome inhibits UV-induced immune suppression. Furthermore, our transcriptome analysis (24 hours after irradiation) showed differential regulation of many genes in the presence or absence of the microbiome, including a predominance of pro inflammatory cytokines versus immunosuppressive cytokines. These findings suggest that the skin microbiome diminished the immunosuppressive response to UV, by modulating cellular and immune function.

Poster 1-18 The premature gut microbiome and the influence on neonatal immunity, brain development and white matter injury - the PreMiBraIn study Seki David, Lukas Wisgrill, Vito Giordano, Katharina Goeral, Angelika Berger, Kathrin Klebermaß-Schrehof, David Berry Division of Microbial Ecology/University of Vienna, Vienna, Austria

The physiological immaturity of extremely premature infants is challenged by a precipitated exposure to extrauterine environments. Microbial colonization of the premature gut starts immediately at birth and successively evolves towards the establishment of a diverse community throughout hospitalization. This ecological process is connected to the isochronal maturation of the infants immune-system and neurophysiology. Recent research revealed that distortions in microbial colonization induce secretion of pro-inflammatory cytokines, prompting an inflammatory response that can result in severe neurophysiological morbidities. However, the mechanisms that mediate homeostasis or dysbiosis remain poorly understood. Therefore, the overarching aim of the PreMiBraIn study is to elucidate those underlying mechanisms within the gut-immune-brain axis in extremely premature infants (<28th weeks of gestation, <1000g). We employed flow cytometry and multiplex protein quantification to assess phenotype and function of regulatory, helper and and T cells in premature infants. 16S rRNA sequencing was used to assess microbial diversities in the premature gut. Furthermore, amplitude-integrated electroencephalography (aEEG), cerebral near-infrared spectroscopy (cNIRS) and visual evoked potentials (VEP) were used to characterize neurophysiological development during hospitalization. Our results suggest that the dynamics in microbial colonization exert major influences on abundance and function of different T cell populations in premature infants, channelling different immunological characteristics between healthy and diseased patients, whereat diseased infants exhibit a pro-inflammatory profile accompanied with a suppressed production of neuroprotective factors. Based on the identification of such factors we enhance our effort to investigate underlying mechanisms to deepen our understanding of co-developing immunology, neurophysiology and microbiology in premature infants.

Poster 1-19 Correlation networks of the human gut microbiome reveal decoupling between phylogeny and function in patients challenged by chronic inflammatory disease Franziska Bauchinger, David Berry Division of Microbial Ecology, University of Vienna, Vienna, Austria

The human gut microbiome is characterized by substantial inter- and intraindividual variability, especially on a phylogenetic level. Those compositional differences are of particular importance in the light of inflammatory diseases, su h as C oh s disease a d ul e ati e olitis, hi h a e li ked to a dys iosis of the i testi al microbial community. Functional variability across individuals seems to be less pronounced, but the mechanisms behind this decoupling of phylogeny and function are poorly understood. Correlation networks are a powerful tool to uncover candidate relationships and interactions in microbial communities. Here, we analyzed an extensive dataset of paired metagenome and metatranscriptome samples (Schirmer et al. 2018, https://i d d .o g that o sists of sa ples f o pa ti ipa ts diag osed ith C oh s disease o ul e ative colitis as well as healthy individuals. We constructed sparse correlation networks from both metagenome and metatranscriptome data. This enables us to compare phylogenetic and functional properties of the gut microbiome, and to characterize microbial species and metabolic processes across individuals and in the light of health status. The network derived from metatranscriptome data shows a strong longitudinal clustering of samples from the same participants, a pattern much less pronounced in the network based on metagenomic data. This result highlights an apparent decoupling between phylogenetic and functional profiles in the gut microbiome as well as strong individual clustering, rather than dynamics driven by inflammation. Our research is aimed towards a better understanding of the mechanisms behind gut microbiome variability and the development of promising approaches towards microbiota-targeted intervention in dysbiotic states.

Poster 1-20 Diversity loss in subgingival microbiota of children with palatal expanders: a case control study E. Santigli, B. Schinagl Division of Orthodontics and Maxillofacial Orthopedics, Dept. of Dentistry and Maxillofacial Surgery, Medical University of

Graz, AUSTRIA

Aim: Bacterial biofilm on fixed orthodontic appliances is suspected to shift oral microbiome compositions versus a diseased state. This study monitors the subgingival microbiome composition to detect shifts due to tooth borne palatal expanders (BAPE). Materials and Methods: The subgingival microbiome of children wearing BAPE (CA, n=16) and an untreated control group (CO, n=16) was compared. Subgingival biofilm was sampled at 3 points in time: T1, baseline; T2, after a three weeks standardized oral hygiene program and T3, after 4 months on the day of the removal of the appliance in CA. Pooled paper points sampling was performed and bacterial DNA analyzed with 454-pyrosequencing targeting V1-V3. Data was processed with ACACIA, QIIME 1.9 and statistical analysis done in R 3.1.2. Results: In rarefaction curves species richness decreased in CAs at T3. Shannon indices present a significantly lower diversity of CAs T3 compared to COs. In NMDS microbiota in CAs cluster clearly at T3 while they were evenly distributed at the other points in time in CAs and COs. LogFC analysis shows significant losses on genus level in Veillonella (-5.32), Leptotrichia (-2.48), Paracoccus (-2.8), Caponocytophaga (-3.24), Parascardovia (-4.38) and Corynebacterium (-2.65). Fusobacterium (2.51), Clostridiaceae (3.97) and Atopobium (7.73) instead significantly gained. Conclusion: A diversity loss after wearing BAPE for four months was found in the subgingival microbiome of children. Seeing this as a marker for the onset or a consequence of disease, we suggest long-term studies to monitor microbiome behavior after removal of the appliance.

Poster 1-21 Carbohydrate load and gut permeability during short term interaction Angelo Ascani Division of Endocrinology and Diabetology, Medical University of Graz, Austria

Tight Junctions (TJs), major regulators of epithelial permeability, are dynamic elements which readily adapt to a variety of developmental, physiological, and pathological circumstances (Fasano, 2000). An abnormal barrier functio of the i testi al epitheliu , des i ed as leaky gut , see s to o espo d to a e ually a o al increase of serum Zonulin levels in a variety of conditions associated with chronic low-grade inflammation and diseases of autoimmunological pathomechanism (A Tarko, 2017). A common trait which generally accompanies metabolic syndromes and chronic low-grade inflammation states is glucose intolerance and hyperglycemia. Hyperglycemia causes tissue damage and fosters the development of endothelial dysfunction (Giacco, 2010). Very recently Thiass et al. (2018) demonstrated how hyperglycemia and serum glucose levels, rather than obesity, may be a direct and specific cause for intestinal barrier dysfunction. The influence of gut permeability on the pathogenesis of chronic low-grade inflammation in metabolic syndromes is complex and not entirely clear, as many components influence the final clinical presentation. The distinction between primary pathological changes from secondary environmental disruptions, differentiating the effects of obesity and insulin resistance on the metabolic changes which are diagnostic features, remains a challenge. Our study aim is to investigate the possible driving effect of sucrose loads on gut permeability in short term, in an attempt to isolate the pathophysiological effects in view of clinical, hormonal and metabolic as well as general parameters such as BMI and age.

Poster 2-1 Methylation-dependent studies on plant-growth associated bacterial strains Manuel Reisinger, Henry Müller and Gabriele Berg Department of Environmental Biotechnology / University of Technology, Graz, Austria

Plants live closely associated with microorganisms that provide beneficial functions. Bacterial strains capable of exerting such plant-beneficial functions have long since been isolated by researchers and employed as inoculum to improve plant health and growth. This project aims to shed light on the role of DNA methylation as an epigenetic regulatory factor for host and niche specific adaptation of plant-beneficial bacteria. In particular, we focused on phylogenetically closely related strains belonging to the genera Serratia and Stenotrophomonas, which are already well known for their plant-growth promoting and stress protecting capabilities. Despite the high genotypic similarities, the colonization competence and the ability to exhibit beneficial effects ad planta are host-specific. Gene-by-gene comparison revealed that the present repertoire of genomic features alone cannot explain the strain-specificity of the plant-microbe interactions. All strains possess distinct restriction-modification systems, suggesting that the epigenotype determines the specific phenotypes. Furthermore, we observed differences in DNA methylation patterns in response to plant root exudates present in the culture media. These findings suggest that the ability of bacteria to respond and interact with plants is not only attributable to the presence of appropriate genes per se. The ability to concert their expression and regulation by epigenetic means, such as DNA methylation, is likewise a contributing factor. The results of this study will advance our understanding of the interplay between genotype, methylotype and phenotype of phylogenetically closely related plant-beneficial bacterial strains with regard to their plant-host specificity.

Poster 2-2 In the search for antimicrobials: functional metagenomics applied to plant microbiomes Christina A. Müller, Stephanie N. Hollauf, Florian Hesch, Leona Graf, Gabriele Berg Institute of Environmental Biotechnology, TU Graz, Graz, Austria

The rapid development and uncontrolled spread of antibiotic resistances is a major problem that our society is currently facing. Hence, finding solutions is a key challenge of the 21st century. With this in mind we investigated the peat moss (Sphagnum magellanicum) associated microbiome as a valuable source of bioactive molecules, with possible applications in biotechnology and medicine. Peat mosses have been used historically in the treatment of infections, based on their antimicrobial properties. In the search for natural products like antibiotics and antimicrobials produced by nonribosomal peptide synthetases (NRPSs) we applied fu tio al etage o i s , a te h ology that e a les the ide tifi atio of biosynthetic gene clusters, which are responsible for the production of natural products of microbial origin. A metagenomic clone library was generated and screened for NRPS-containing sequences by a PCR-based method. Thirteen clones were detected and from those, two clones were selected for whole-insert sequencing and cloning. This led to the discovery of two novel NRPS-gene clusters, which are presumably involved in the production of antimicrobial compounds. The first cluster consists of a membrane-associated synthetase that shows structural similarities to homopoly(amino acid) producing synthetases, an unusual class of NRPSs. The second gene cluster contains three synthetases and other auxiliar enzymes, and might synthetize a new type of antibiotic. Our results demonstrate that the plant microbiome is a highly valuable and yet less explored resource in the field of natural product discovery. Moreover, our metagenomic studies provide an interesting insight into the molecular diversity and the biosynthetic potential of the plant-associated microbiome.

Poster 2-3 The vertical transmission of the tomato plant microbiome is influenced by environmental conditions A Bergna, T Cernava, M Rändler, R Grosch, C Zachow, G Berg acib GmbH, Institute of Environmental Biotechnology, TU Graz, Graz, Austria

Due to the increasing agricultural demand, biotechnological solutions able to sustaining plant health in an effective and persistent way are becoming crucial. For this reason, the research for novel bacteria-based biologicals should consider, aside from their effectiveness, the stability across plant genotypes, compartments and generations. To understand how beneficial bacteria are distributed across a whole tomato plant system (soil, first generation seeds, rhizosphere, root-endosphere and second generation seeds), an approach combining the characterisation of bacterial isolates and bacterial community analysis by 16S rRNA gene metabarcoding was employed. The bacterial community of each plant compartment among cultivars showed distinct signatures and levels of complexity. Cultivation approaches detected plant-beneficial bacteria assigned to Bacillus sp., Stenotrophomonas sp., and Ralstonia sp. in all studied microenvironments. Despite the large reservoir of bacterial diversity harboured by the soil, the seed appeared to be the key vehicle for the transmission of beneficial bacteria. The seed core microbiome was predominated by the families Burkholderiaceae, Pseudomonadaceae and Comamonadaceae. Moreover, Ralstonia pikettii was present in both seed generations and in the soil; interestingly the reduction of this taxon between the first generation (grown in field conditions) and the second (grown in pathogen-free and low-nutrient experimental conditions) was counterbalanced by a significant augmentation of the well-known PGPR Massilia. This generational shift in the seed microbiome suggests that the vertical transmission of beneficial bacteria might be influenced by environmental conditions.

Poster 2-4 Controlling the Meloidogyne disease complex in Ugandan tomatoes Adrian Wolfgang, Julian Taffner, Rafaela Araúji Guimarães, Danny Coyne, Gabriele Berg Institute of Environmental Biotechnology, Graz, Austria

Nowadays, agriculture is confronted with increasing incidences of soil-borne pests and pathogens, which often lead to synergistic yield losses and are difficult to control. Root-knot nematodes (Meloidogyne spp.) in combination with plant pathogenic fungi are a serious threat to agriculture especially in tropical climates. To get insights into the serious Meloidogyne disease complex and to find control options, we studied the microbiome and volatile-based control mechanism in Ugandan tomatoes by a multiphasic approach combining antagonisms studies of a strain collection and analyses of 16S rRNA gene amplicon libraries. Highly specific antagonism towards either fungal pathogens or root-knot nematodes were found within our strain collection. All antagonists were identified as substantial part of the microbiome and represent approximately 6 % of the healthy and diseased tomato root microbiome. However, bacterial alpha diversity of galls differed both qualitatively and quantitatively from healthy roots, while composition of the bacteriome of the rhizosphere and healthy endosphere only differed in abundances. The highly specific antagonism found suggest a combination of volatiles or VOC-producing bacteria for with other control strategies.

Poster 2-5 Mosquitos are mixing vessels for interspecies viral microbiomes Jakob Thannesberger, Ingeborg Klymiuk, Nicolas Rascovan and Christoph Steininger Abteilung für Infektiologie und Tropenmedizin/Medizinische Universität Wien, Vienna, Austria

Mosquitoes are the most important vectors for arthropod born virus infections on a global scale. Infectious pathogens such as Dengue virus are highly adapted to their arthropod vector. Nevertheless, mosquitoes carry also other mosquito- specific viruses. Thus, mixed viral infections of mosquitoes allow genetic recombination of diverse viruses, turning mosquitoes into potential virologic mixing vessels. Advances in NGS have expanded our knowledge on the richness of viruses harbored by arthropods. Yet, little is known about the actual composition and sources of the mosquito virome as in most of previously conducted studies only 1-5% of metagenomic reads were of viral origin. In our study, we tested Aedes aegypti mosquitoes from a tropical region (Barbados) and compared their virome profile to Culex spp. mosquitoes from the same habitat by applying our previously developed virus purification and enrichment protocol (VIPEP), combined with a metagenomic NGS based approach. We found that 47% of reads matched viral database sequences of 152 virus taxa with nucleotide sequence similarities from 64% - 99%. We traced back the sources of the mosquito virome, identifying four big reservoirs of viral infection and colonization: (i) known mosquito specific viruses (ii) viruses of animals or humans that mosquitoes feed on (iii) viruses isolated from feces of animals, feeding on mosquitoes (erroneously annotated as animal viruses) and (iv) environmental viruses colonizing mosquito chitin surfaces. Our results highlight the wide spectrum of viral mosquito infections and suggest further metagenomic mosquito surveillance to be considered as prediction tool for disease epidemics at an early stage.

Poster 3-1 Development of indoor microbiome in newly built hospital Mantaj P, Duller S, Brunner D, Farthofer D, Moissl-Eichinger C, Koskinen K Medical University of Graz, Austria

This poster presentation details a study on the microbiome of the newly build surgical department building at the hospital of the Medical University of Graz, Austria. With its opening in June 2017, together with staff and patients, a diverse community of microorganisms moved in. The exposure to these indoor microorganisms has an important impact on human health, particularly in a hospital environment where the range of microorganisms is constantly changing. To take a close look at this community of microorganisms, samples from the department of General and Thoracic Surgery were taken on six different timepoints (before and 1, 4, 12, 26 and 52 weeks after moving) from different surfaces around the patients such as lights, floors under patients beds, medical workplace surfaces, bathroom sinks and frequently touched items such as pillows, water taps, door handles, remote controls and toilet flush buttons. After DNA extraction and amplification (by PCR) of the hypervariable region V4 of the 16S rRNA gene, Illumina MiSeq sequencing, and analysis of antibiotic resistance genes, the variety of microorganisms and their features are statistically analyzed with regard on transmission within and between the departments and appearance in different time points. In this poster presentation we will summarize the latest results of this project. These results could help to understand the range of microorganisms which live in hospital surroundings and their spread through the building, identify the operational characteristics of buildings that influence these microbiomes, and change indoor ecosystems in a way to prevent the spread of nosocomial pathogens.

Poster 3-2 Interplay of hospital microbiome and resistome – Connecting pathogenic infection risk, healthy microbes and environmental biodiversity in a functional hospital setting Stefanie Duller, Alexander Mahnert, Christine Moissl-Eichinger, Kaisa Koskinen Department of internal Medicine, Medical University of Graz, Austria

Hospital acquired infections are a serious problem worldwide. In Europe there are three million cases of these infections annually, of which 50.000 are fatal. Resistance is common, and despite strict disinfection procedures, resistant (pathogenic) bacteria are frequently found on hospital surfaces. Consequently, the microorganisms that inhabit hospital indoor environment can influence the patient recovery and outcome, and potential link between hospital indoor environment-associated microbial communities and hospital-acquired infections has been suggested. In this project we explore the microbiomes and resistomes of different hospital areas and sites with various cleaning and disinfection procedures, and study if purposely increased environmental biodiversity in hospital can decrease the prevalence of pathogenic microorganisms and the extent of horizontal gene transfer. We correlate the resistome information (epicPCR, plasmidome) and 16S rRNA gene-based microbial community composition with degree of confinement, cleaning and disinfection procedures, and microbial diversity. Our focus is on the whole microbial communities, and their relation to the pathogenic, life-threatening organisms. Resolving the bacterial community structure in hospital environments will be critical for understanding the dissemination of antibiotic resistance genes and development of antibiotic resistance. The results will help us to understand the microbial dynamics in the hospital indoor environment and to support safe recovery of the patients. The latest results will be presented at the symposium.

Poster 3-3 Establishing a PMA-based, molecular protocol for microbial life-dead distinction in specialized indoor environments Lisa Wink, Ibrahim Aly, Petra Rettberg, Gerhard Kminek, Christine Moissl-Eichinger Medical University of Graz, Austria

Microbial contamination and quality control usually relies on cultivation and quantification of colony forming units. This process, however, is laborious and gives only information on the cultivable microbial diversity. One field, which requires quick decisions on relevant microbial contamination, is Planetary Protection. Herein, mission goals, such as other planets, need to be protected from terrestrial microbial contamination. This includes a stringent quality control of spacecraft. To avoid delays in construction and testing, decision on spacecraft cleanliness have to be taken in timely manner. In collaboration with the German Aerospace Center and the European Space Agency, we are establishing a novel protocol for the quick analysis of cleanroom and spacecraft contamination, based on the application of propidium monoazide (PMA), which blocks the signal from non-viable cells. Classical cleanroom contaminants were selected to form a representative mock community for all experiments. We simulated cleanroom sampling and sample concentration on filters. After exposure to radiation, desiccation and freezing, stresses which are expected during a space flight, the filters are treated with PMA, subjected to DNA extraction, microbiome analysis and quantitative PCR. In parallel to confirm our results, cultivation-based tests are performed. Our results indicate that the protocol developed is well suited for a quick (about 14 h) quality assessment of the viability of possible contaminants. We also could show, based on the stress-exposure that the viability of the mock community is largely reduced. This protocol might also be useful for applications in the field of hygiene, food contamination control or pharmaceutical industry.

Poster 3-4 Broad spectrum pathogen detection (bacteria and fungi) by NGS is a novel measure for tissue based infectious disease diagnostics Andrea Thüringer, Gregor Gorkiewicz, Karl Kashofer Institute of Pathology, Medical University of Graz, Austria

Diagnosis of infectious diseases is a common task in molecular pathology but standard microbiological methods frequently fail to reveal causative pathogens. Microbial 16S rRNA gene and fungal ITS (internal transcribed spacer) sequencing by NGS has recently emerged as a versatile tool for research but can also be utilized for infectious disease diagnostics in molecular pathology. Variable regions of the bacterial 16S rRNA gene and the fungal ITS regions were amplified by PCR and sequenced using Ion Torrent S5XL, error correction, clustering and annotation was performed using open source Qiime 1.8 software. In a four year period we have investigated over 300 clinical cases in which classical microbiological methods failed to reveal causative pathogens. This method is especially effective in diagnosis of infectious diseases of solid organs (e.g. heart, brain, lung, liver) wherein a high percentage of atypical pathogens including rare diseases like tula e ia, atypi al a dia al e e do a ditis hipple s disease a d poly i o ial i fe tio s ould e revealed. Detection rates were very high in liver (95%) and heart (70%) specimens. In contrast, agents of putative bone and joint infections were only rarely detected, possibly due to the low bacterial load in these infections being at a level of background bacterial contamination emerging from the environment or specimen workup, sporadic contamination of reagents at the suppliers and trace amounts of bacterial DNA in enzyme cocktails. Bacterial 16S rRNA gene and fungal ITS analysis is a powerful diagnostic tool for unculturable, fastidious pathogens and should be applied if classical microbiology failed to reveal causative agents in histologically suspected infectious diseases.

Poster 3-5 Soil innate microbiota affects the persistence of human pathogens in soil Jasper Schierstaedt, Helena J. Barkowski, Sven Jechalke, Abhishek Shrestha, Kornelia Smalla, Rita Grosch, Adam Schikora Leibniz Institute of Vegetable and Ornamental Crops/ Plant-microbe systems, Großbeeren, Germany

Foodborne diseases are increasingly associated with fresh fruits and vegetables and Salmonella was their second most frequent cause in 2015. The biological diversity of soil plays a major role in the establishment of Salmonella in the plant environment. Antagonists and plant beneficial microbes negatively affect the successful establishment of Salmonella in the rhizosphere. Here we analyzed the interaction between the human pathogen Salmonella enterica, the soil innate microbiome and the crop plants tomato, lettuce and corn salad grown under greenhouse conditions. We observed that Salmonella persisted in the rhizosphere of lettuce and tomato. In contrast, its numbers declined in the rhizosphere of corn salad. Very important was the observation that reduction of microbial diversity in soil increased the ability of Salmonella to persist in this environment. These results clearly show a dependency between the microbial diversity and the potential of Salmonella to colonize the rhizosphere as well as the high physiological plasticity of Salmonella. In the following, we focused on the impact of induced resistance. In greenhouse experiments we primed crop plants by application of the bacterium Ensifer meliloti to the soil close to the roots. This bacterium produces the signaling molecule N-acyl-homoserine-lactone which might induce resistance against Salmonella enterica. Our results show that priming has a negative effect on the persistence of Salmonella. Primed plants are able to express defense related genes earlier than unprimed plants and are able to keep the stomata closed. These results indicate the potential of priming for enhanced resistance against S. enterica.

Poster 3-6 Structural Characterization of the Surface Layer Proteins of Lactobacillus acidophilus T. Sagmeister, E. Damisch, M. Eder, A. Dordic, K. M. Padmanabha Das, U. Hynönen, A. Palva, J. Vonck, M. Oberer and T. Pavkov-Keller Institute of Molecular Biosciences, University of Graz, Austria

Surface layers (S-layers) are 2D paracrystalline lattices of proteins or glycoproteins which cover the whole cell surface of many Archaea and Bacteria. Since these proteins are in close contact with their habitat they fulfil many vital tasks like bacterial adherence to other cells or substrates, protection against life-threatening conditions and maintenance of the cell shape. S-layer proteins of lactobacilli species have a highly basic pI and are between 25-71 kDa in size. They are attached to the cell wall by interaction with lipoteichoic acids (LTA). It is reported that they are involved in auto- coaggregation and adherence and therefore are significant for the stimulation of gut dendritic cells by interacting with specific receptors. Our goal is to characterize the surface layer proteins SlpA and SlpX of Lactobacillus acidophilus, which are both necessary to build up the protective S-layer coat. By changing the composition of the S-layer coat, the organism is able to adapt to the changing environmental conditions and threats, e.g. osmotic stress. For structure-function characterization, we designed several protein fragments. Soluble fragments were purified and subjected to crystallization. Optimized crystals of the C-terminal fragments, containing the LTA-binding domain, diffracted to 1.8 and 2.2 Å. Crystal structures were solved by SeMet-SAD and by molecular replacement. To further characterize the binding of the S-layer to bacterial cell we performed NMR titration experiments and isothermal titration calorimetry measurements with the C-terminal fragment of the protein.

Poster 3-7 Microbiome dynamics and its impact on human space travel Alexander Mahnert, Daniela Brunner, Cyprien Verseux, Kaisa Koskinen and Christine Moissl-Eichinger Department of Internal Medicine, Medical University Graz, Austria

A main driving force behind space exploration is the discovery of new worlds for humankind. During these journeys crew safety and health are challenged by an extreme confinement from the surrounding hostile environment with specific implications for the human microbiome. To better understand microbial dynamics in isolated and confined environments (ICE), front torso skin of 6 crewmembers in an 11-meter-in-diameter dome located on the barren slopes of the Mauna-Loa volcano in Hawaii were sampled together with samples of the habitat/furniture surfaces and during a one-year ICE mission (HI-SEAS IV). The crew was isolated and confined, and hygiene practices were restricted. 181 microbiome samples were analyzed by 16S rRNA gene profiling and qPCR. Longitudinal analysis of pairwise differences between the built environment and the crew over time showed significant differences in diversity for the crew, while samples from the built environment remained constant. Longitudinal analysis of linear mixed effects models revealed that microbial diversity increased slightly in the built environment, and stronger in samples from the crew. Samples from the crew had high relative abundances of typical skin-associated bacteria such as Staphylococcus aureus and Propionibacterium spp. Samples from the built environment were very similar to each other over the whole sampling period, while samples from the crew showed some events of very high dissimilarity, mostly due to an archaeal lineage (up to 80% of Methanobrevibacter). Further work is ongoing to obtain a deep u de sta di g of the i o io e s atu e a d dy a i s th oughout the HI-SEAS IV mission.

Poster 3-8 Harnessing the microalgae microbiome for biotechnology Lisa Krug, Tomislav Cernava, Armin Erlacher, Gabriele Berg Austrian Center of Industrial Biotechnology, Graz, Austria

The industrial relevance of microalgae is steadily increasing and large-scale production is often required to meet the needs for bulk production. Typically, industrial bioreactors harbour a co-cultivated microbiota, which plays a u ial ole fo the algae s fit ess. I o de to ette u de sta d the i pli atio s a d dy a i s of su h communities, we analysed the algae-associated microbiota under natural conditions. During melt season, colored snowfields are frequently detected in the Alps and attributable to psychrophilic algae blooms. By being important primary producers on the snow surface, microalgae allow heterotrophic bacteria and fungi to co-exist in these extreme environments. In natural ecosystems microalgae and bacteria can form close symbiotic relationships similar to higher plants. Therefore, we studied naturally occurring microbiome-algae associations on red, green and orange colored snowfields in two geographically distant locations in the Austrian Alps by 16S and 18S rRNA gene amplicon sequencing. While both red and green snowfields at both sampling sites showed high occurrence of Chlorophyceae, members of the family Chrysophyceae were the most frequently occurring microalgae on orange snowfields. Basidiomycota were present in all sampled snowfields with relative abundances ranging from 25% to 81%. Common bacterial phyla on green and red snowfields on both sampling sites were Sphingobacteria (59%) in particular Solitalea sp., while Betaproteobacteria (69%) were the dominating bacteria on orange snowfields. Co-occurrence network inference analyses revealed that members of the family Oxalobacteriaceae have exclusively positive interconnections, including interactions with Chrysophyceae, Chlorophyceae and Trebuxiophyceae. These results support our hypothesis that the composition of the bacterial community on snowfields is partially driven by the occurrence of certain microalgae species. The understanding of evolutionary evolved microbiome-algae associations and the identification of dominant correlations and putative beneficiary constituents give rise to new co-inoculation strategies in microalgae cultivation.

Poster 3-9 How plant-associated Archaea interact with their hosts Julian Taffner, Armin Erlacher, Anastasia Bragina, Henry Müller, Christin Zachow, Christine Moissl-Eichinger and Gabriele Berg Institute of Environmental Biotechnology, Graz, Austria

Plant holobionts are known to harbour a wide diversity of microorganisms, such as bacteria and fungi, influencing plant nutrition, resistance to stress and fitness. Recent studies have shown that Archaea also shape the microbiome of plants, but their functions and interactions with their hosts remain mostly unclear. To get a broader insight into the community structure, habitat preferences and functions of plant-associated Archaea, we compared 41 different agriculturally used plant-species from the mediterranean area, Austria and Eastern Africa as well as the vegetation of alpine raised bogs from upper Styria (Austria). Therefore we used a combined approach including 16S rRNA amplicon sequencing, whole metagenome shotgun sequencing and fluorescence in situ hybridization confocal laser scanning microscopy (FISH-CLSM). The highest relative abundances of Archaea were detected in the endosphere of olive trees (Olea europaea L.), with up to 67.3% of total reads, in dwarf shrubs (Vaccinium myrthillus and V. oxycoccus, with 33.0% and 31.7% respectively), and in the rhizosphere of sugar beets (Beta vulgaris L.) with 20.0%. Across all habitats, the archaeal community structure was dominated by Euryarchaeota or Thaumarchaeota, followed by the less abundant phylum of Crenarchaeota, except in O. europaea, where Thaumarchaeota were predominant. On plants, we observed signatures for putative adaptation mechanisms of Archaea for their hosts, including those for higher chemotaxis, nutrient cycling like CO2 fixation, stress response, especially against oxidative stress, archaeon stability, and possible plant growth promotion through auxin. These findings reveal a so far unobserved role of Archaea for plant holobionts.

Poster 3-10 The microbiome of sclerotia of soil-borne fungal pathogens – a hot spot for interactions between potential biocontrol agents and phytopathogenic fungi Pascal Mülner, Philipp Wag e , Alessa d o Be g a, Dže a a Sa ajli , Ba a a Gstötte ay , K isti Dietel, Rita Grosch, Tomislav Cernava, and Gabriele Berg ABiTEP GmbH, Institute of Environmental Biotechnology, Graz, Austria

Soil-borne plant pathogens are an extremely increasing problem in modern agriculture and their ability to survive long periods in soil as persistent sclerotia makes control and treatment particularly challenging. To develop new control strategies, we explored the microbiome associated with sclerotia of Sclerotinia sclerotiorum and Rhizoctonia solani, two soil-borne fungi causing high yield losses in a broad host range. We used a combination of methods to get insights into the indigenous microbiome of sclerotia, to compare it to microbiota of the unaffected potato skin and surrounding soil and find novel biocontrol agents. A 16S rRNA amplicon study showed that the sclerotiome of R. solani is highly similar to the microbiota of enclosing soil, while microbial communities of potato peel display significant differences. Distinctive bacterial lineages were associated with healthy and sclerotia-affected tuber surfaces. Flavobacteriaceae and Caulobacteraceae were primarily found in unaffected areas, while Phyllobacteriaceae and Bradyrhizobiaceae were associated with the presence of sclerotia of Rhizoctonia solani. Bioactive volatile compounds emitted by isolates of Bacillus, Pseudomonas and Buttiauxella exhibited high antagonistic activity towards the soil-borne pathogens. Differential imaging showed that volatiles emitted by the antagonists altered the morphology of sclerotia and increased the layer of non-viable hyphae. Distinct combinations of antagonists increased the inhibition of R. solani up to 60% when compared to single isolates. The integrative sclerotiome assessment showed that fungal survival structures are associated with a specific microbiome, which is also a reservoir for new biocontrol agents.

Poster 3-11 Bacteria and Fungi: how do they communicate? Filomena Nogueira1,2,3, Michael Tscherner3, Sabrina Jenull3, Niko Popitsch2, Leonel Pereira1,2,3, Karl Kuchler3 & Thomas Lion1,2,4 1Labdia Labordiagnostik GmbH, Vienna, Austria

2Children's Cancer Research Institute, Vienna, Austria

3Medical University of Vienna, Max F. Perutz Laboratories, Vienna, Austria

4Department of Pediatrics, Medical University of Vienna, Austria

The interactions between pathogens occurring during polymicrobial infections remain poorly understood. Only recently, with the expansion of microbiome research, scientists became aware of the complex relationships between microorganisms. Importantly, opportunistic bacteria and fungi that have been living as commensals may turn into pathogens. Such alterations cause an imbalance of the microbiota that must be taken into account for diagnostics and treatment of infections. Often, bacteria and fungi occupy the same niches which results in either a synergistic or antagonistic interaction. Bacteria and fungi communicate via secretion of quorum sensing molecules and production of virulence factors which may also impact the response of the immune system and induce alterations in the host. Therefore, we aim to characterize the interaction of relevant human pathogens that occupy the same niches such as Candida, Aspergillus and Klebsiella. The capacity of biofilm formation and structural integrity of bacteria and fungi alone and in co-culture were assessed by crystal violet staining, confocal microscopy and qPCR. Our data have shown a suppressive effect on fungal growth and biofilm formation by the bacteria in an in vitro co-culture. However, fungal growth could be restored upon antibiotic treatment. Analysis of the cell viability has also shown that the bacteria do not kill the fungus but rather exert a suppressive effect. Furthermore, omics analysis revealed key factors mediating Candida, Aspergillus and Klebsiella interaction. Molecules identified as regulators of this interaction will provide novel insights potentially exploitable for diagnostics and treatment of polymicrobial infections.