Bioweek talk 2012

EXTINCTION OF MICROBES... SHOULD WE CARE?

Marilen M. Parungao-Balolong, MSc, SMicAssociate Professor

Bioweek 2012 BIOSeminar

Wednesday, August 15, 2012

WE ALWAYS CARED ABOUT PLANT EXTINCTION

WE ALWAYS CARED ABOUT ANIMAL EXTINCTION

WE ALWAYS CARED ABOUT HUMAN EXTINCTION

BUT...MICROBES? ALWAYS TAGGED AS

THE REASON FOR EXTINCTION...

MICROBES: THREAT TO PLANTS

Phytophthora infestans = Europe and Ireland, (1840)

Hemileia vastatrix or coffee rust Ceylon (1860s)

Cratocyctis ulmi = Dutch Elm Disease (1900s)

MICROBES: THREAT TO HUMANS

BLACK DEATH & SPANISH FLU

MICROBES: THREAT TO ANIMALS

CAN MICROBES FACE EXTINCTION?

“Extinction is a Principle of Evolution”

EXTINCTION

• Over 99% of the species that have ever lived have become extinct

• Guesstimate: we lose about 1 species per day

• CURRENTLY: they say that we are living in a period of mass extinction (6th) = brought about by human activity as driving force

“Microbes are Everywhere”

ca. 4 to 5 × 1030 prokaryotic cells on Earth, with the open ocean, soil, and oceanic and terrestrial

subsurface showing the highest abundances

A typical coastal water sample contains 107 viruses, 106 bacteria and

103 protists /ml

Microbes come in diverse forms; however, it is not known how many different species of microbes inhabit the planet....WHY?

• problems involved in defining a microbial species

• majority of prokaryotic cells cannot be easily grown in culture, which is a prerequisite for species identification of microbes

• NOTE: Only about 5000 to 6000 prokaryotic species have been formally described

With the birth of NON-CULTURE METHODOLOGIES....

• At least 1800 species and 1.2 million new genes were found using a shotgun sequencing approach of microorganisms from a single sample in the Sargasso Sea (Venter et al. 2004)

• About 643 new species were identified using a 99% similarity as delineation between prokaryotic phylotypes or species based on 16S rRNA gene sequences (Venter et al. 2004)

• Up to 7000 viral types have been detected using a metagenomics (community genomics) approach and it is believed that viruses represent the largest unknown sequence space (Breitbart et al. 2002)

PROKARYOTIC MICROBES AS SHAKERS & MOVERS OF THE

BIOSPHERE

• They invented photosynthesis long before eukaryotes evolved

BIOSPHERE

• Their oxygen production changed the atmosphere to the oxygenic status we are currently experiencing

BIOSPHERE

• Microorganisms degrade and remineralize organic material, others produce methane, reduce sulfate to sulfide, integrate molecular nitrogen or change the forms of inorganic nitrogen

BIOSPHERE

• Microorganisms degrade and remineralize organic material, others produce methane, reduce sulfate to sulfide, integrate molecular nitrogen or change the forms of inorganic nitrogen

• Microorganisms drive the global cycles of carbon, nitrogen, phosphorus and sulfur

“WITHOUT MICROORGANISMS

ALL OTHER LIFE FORMS WILL NOT

SURVIVE”

SO HOW DO THEY ADAPT...

• Symbiosis

• between multicellular organisms with microorganisms showed great evolutionary success (e.g. Lichens = 1500 species)

• Symbiosis

• between plant roots and fungi (mycorrhiza) = reason for spread of plants in the continents

• Symbiosis

• between coral host and photosynthetic dinoflagellate

• coral host obtains sugars from the algae and the interference of algae with carbon cycling enhances calcification

• reason why coral reefs one of most diverse ecosystem

• Exchange of Genes (Horizontal Gene Transfer or Microbial Sex)

CONSEQUENCES OF GENE TRANSFERS

• Cohan (2001)

• gene transfer among species increases diversity

• gene exchange can help to sustain co-existence of genetically different ecotypes

• gene exchange would help protect ecotypes from extinction if the adaptive mutation can be transferred

BIOGEOGRAPHY OF MICROBES

ON DISTRIBUTION• Finlay & Fenchel 1999

• “there are no distributional barriers for small free-living organisms such as microbes”

• Finlay et al. 1996

• “global species diversity is inversely related to body size”

• suggests that the shear number of protists makes global dispersal very likely by mechanisms such as hurricanes, ocean circulations, groundwater connections, damp fur, etc

ON EXTINCTION

• Cohan, 2001

• “the large number of microbial cells per species makes extinction unlikely, extinction is not a threat”

• works only for “free-living microbes”

ON ENDEMICITY

• More evidence of endemicity and biogeography is available for microorganisms associated with plants or animals

• Hosts can be considered as islands, which permit the development of endemism in prokaryotes

EVIDENCE OF EXTINCTION

EVIDENCES

• Local extinctions (or strong reductions in the abundance of microbial species) probably occur quite frequently, e.g. due to clearing of forests, agricultural activity or erupting volcanoes

• a multicellular organism is best regarded as an association of species — a mini-ecosystem — and many of these species exist only in this association (e.g. coral reefs destruction, microbes in Dodo or mammoth etc)

MICROBIAL FOSSILS?

ARE THERE FOSSILS TO GUIDE US?

• Listgarten & Loomer 2003

• Detection of microbial fossils is difficult compared to detection of plant and animal fossils

• one of the reasons for our lack of knowledge on extinction rates of microbes.

• Stromatolites (microbial reefs) were globally distributed in the Proterozoic but the abundance decreased markedly and at present there are only a few sites left

• suggests at least local extinctions in the geological past

ENDANGERED

• Most free-living microbes are likely not endangered, although their local distribution might vary considerably and local extinctions

• However, associated species may be ‘threatened’ in the same way as the multicellular hosts organisms

THE INFECTIOUS PARTICLE...

• Emiliani 1982, 1993

• Microbes may also become extinct when one partner in a predator – prey or parasite – host system loses the adaptation race

• Example: As long as the virus cannot find an alternative host, this means self-extinction

SO...SHOULD WE CARE ABOUT THE POTENTIAL LOSES

OF MICROBIAL SPECIES???

RECALL...the prokaryotic DNA world constitutes a

‘global superorganism’ that shares the gene pool by

horizontal gene transfer, the microbial ‘kamasutra’

(Doolittle 1999)

WITHOUT THEM...CHANGES IN BIOGEOCHEMICAL

CYCLING

WITHOUT THEM...CORAL BLEACHING

YOUR CONTRIBUTION

TO THEIR EXTINCTION

OUR CONTRIBUTIONS TO POSSIBLE EXTINCTION

• antimicrobials

• habitat fragmentation

• pollution and contamination of aquatic systems

• The BIGGER THREAT: Climate Change

EXTINCTION OF MICROBES... WE SHOULD CARE!!!

THANK YOU VERY MUCH!!!

Bioweek talk 2012

Technology

!2012 OER Talk

Tarporley Talk July 2012

RiverWalk & Talk: February 2012

2012 oslo-talk

DEXA 2012 Talk

Tiger Talk - January 2012

Property Talk October 2012

Tarporley Talk September 2012

2012 wellcome-talk

Peace Talk June 2012

IPv6 Security Talk 2012

Tech Talk 2012

broncolor Tech Talk 2012

Grace Talk July 2012

ICRA 2012 talk

ESA 2012 talk

Tarporley Talk November 2012

Winter 2012 Girl Talk

Tawe Talk February 2012

Tree Talk April 2012