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1!
www.icbm.de/pmbio
Microbial Ecology
Anthropogenic habitats
Anthropogenic habitats
Sewage and drinking water Waste water treatment and water purification
Crude oil deposit Microbial degradation of hydrocarbons
Ore deposit Microbial leaching of metals
2!
Hygienic und safe water supply is the essential requirement for healthy human civilization and
prevention of epidemic!
Average water consumption per person and day (Germany): 150-200 l drinking water
Main source for drinking water: Groundwater (well or springs) Surface water (dam like water reservoirs or lakes)
Drinking water must be free of all kinds of germs!
Regulated by EU-guidelines and by the national drinking water regulation
Controlled and analyzed by independent institutions
Next to microbial analysis, physical and chemical regulations
Water hardness: depend on amount of calcium- und magnesium compounds (earthy alkali compounds)
Drinking water should be 5-25˚dH (1 ˚dH = 10 mg/l CaO)
3!
Coliforms as indicator organisms
Detection of coliforms indicate pollution of faeces
Phylogenetic group of Gram-negative, facultative aerobic, non-sporeforming rods
Coliforms include typical microbes of the intestinal tract: Escherichia coli, Klebsiella pneumoniae
Coliforms in drinking water behave like many pathogenic microorganisms
Coliform colonies growing on a membrane filter
4!
Water purification plant
Effect of water purification on the incidence of waterborn diseases in Philadelphia
5!
Vibrio cholerae (Gram negative gamma-proteobacterium)
Discovered by John Snow (1854)
Occur in many aquatic environments
Cause Cholera disease! (Lost of water and electrolytes, dehydration)
Transmitted by drinking water
Bacteriophages encode the cholera toxin
6!
7!
Distribution of Cholera disease (2004)
Sewage treatment Sewage is polluted with different compounds that are not allowed to discharge into natural water system
Microorganisms in sewage: 106-108 Bacteria per ml (ca. 10 Pathogenes per ml) 103-105 fungi (yeast) per ml
Composition of organic compounds: 50% carbohydrates, 40% proteins und urea, 10% fatty acids
Main problem: urea and phosphates
8!
Sewage treatment
Goals: Elimination of pathogens
Mineralization of organic substances
Removing of N and P (limiting nutrients for primary producers)
Application of chemical, physical and microbiological methods
Principle waste water treatment processes
9!
Primary treatment
Flow-diagram of waste water processes with primary treatment
10!
Discontinuous activated sludge treatment (batch-mode)
Anoxic secondary waste water treatment
11!
Anaerobic, biological level - digestion tower
12!
Continuous activated sludge method (flow-mode)
Komplexe Polymere (Polysaccharide, Lipide, Proteine)
Monomere (Zucker, Fettsäuren, Aminosäuren
Kurze Fettsäuren + Alkohole (Lactat, Butyrat, Propionat, Ethanol)
H2 + CO2 Formiat
Acetat
Hydrolyse
Fermentation
CO2 + Methan CO2 + Sulfid
Anaerobe Abbau von organischem Material
Sulfatreduzierer (Desulfo-) Methanogene (Methano-)
13!
Nitrification: Oxidation of ammonia to nitrate
Performed by two physiological microorganism clades
1.! Ammonia-oxidisers (Nitroso-) z.B. Nitrosomonas europaea
2 NH3 + 3 O2 ! 2 NO2- + 2 H2O + 2 H+
2. Nitrite-oxidiser (Nitro-) z.B. Nitrobacter winogradskyi
2 NO2- + O2 ! 2 NO3
-
14!
NO3-
NO2-
NH4+
N2
NO
N2O
Nitrate reducers
Nitrate reduction
Denitr
ification
Nitrite ammonification
Denitrification - Reduction of nitrate to nitrogen
Anaerobic respiration with inorganic nitrate as electron acceptor
Formation of gaseous compounds nitrous oxide (N2O), nitric oxide (NO) und nitrogen (N2)
Results in a loss of nitrogen in the environment (agriculture - wastewater treatment)
Initial step is catalyzed by the nitrate reductase
Many facultative anaerobic prokaryotes are denitrifiers
15!
Physiology and Diversity of Prokaryotes WS 2006/2007 (www.icbm.de/pmbio/)
Nitrate (NO3-)
Nitrogen (N2)
+ V
0
Oxidation state
Reduction
5 electrons (e-)
Nitrite (+III)
Nitric oxide (+II)
Nitrous oxide (av. +I)
2NO3- + 10e- + 12H+ ! N2 +
6H2O
Denitrification
Elimination of nitrogen
Urea
16!
Urea
Denitrification Nitrate -> N2
5<CH2O> + 4NO3- + 4H+ -> 5CO2 + 7H2O + N2
Nitrification Ammonia -> Nitrate
Elimination of nitrogen
17!
Oil
Complex mixture of lipophilic compounds embedded in the Earth crust
Consist of up to 600 different compounds (86% hydrocarbons)
Most important energy resource and precursor for chemical industry
Formed by biological processes over geological time periods (diagenesis)
18!
Crude oil degrading microbes
Aerobic degradation: catalysed by oxygenases (fungi, Pseudomonas)
Anaerobic degradation : Fumarate addition (Sulfate- and nitrate-reducers)
Bacteria in the oil/water-interface
19!
Biodegradation of herbicide
20!
Microbial processes in industrial and environment remediation
Terrestric Composting Land fill Remediation of polluted soils Microbial leaching
Limnic & marine Sewage treatment Drinking water purification Remediation of pollutions
Metal recovery by
Microbial leaching
Abb.: Spektrum der Wissenschaft; Verständliche Forschung: Industrielle Mikrobiologie, 1987
Coppermine near Salt Lake City
21!
Microbial leaching
Recovery of metals form low-ore rocks by acid production and
dissolvement of minerals by acidic bacteria
Often applied on copper recovery (content of copper-ore around 1 %
Cu).
Mainly use for sulfidic ores with covellit (CuS), pyrit (FeS2)
In general, sulfide-metals not or hardly soluble
Acidic conditions increase solubility of metals
Release of Cu2+ from ore by
addition of Acidithiobacillus
ferrooxidans (blue) and in in a
sterile control experiment
(red).
Zeit
[Cu2+]
Minerals that react more easily
with air are also better oxidized
by microbes (FeS>CuS>PbS).
Increase of copper dissolving by bacteria
(Acidithiobacillus ferrooxidans)
H2S react spontaneously with oxygen of
the air
Metal-sulfides also react with O2, but
extreme slow.
22!
Microbial processes during microbial leaching
Acidithiobacillus ferrooxidans oxidize metals (Cu+, Fe2+) as well as sulfide
Copper leaching 1. Cu2S + O2 CuS + Cu2+
(aq) + H2O
2. CuS + O2 Cu2+ + SO42-
3. CuS + 8 Fe3+ + 4H2O Cu2+ + 8 Fe2+ + SO42- + 8 H+
Fe3+ represents a good oxidant for
sulfide minerals and can be reoxidized
by A.!ferrooxidans.
Abb.:
Spe
ktru
m d
er W
isse
nsch
aft;
In
dus
trie
lle M
ikro
bio
logi
e, 1
98
7
A. thiooxidans on S0
(15 000 times) Other application: Recovery of gold and uranium
23!
24!
25!