microbial ecology - uni oldenburgsewage treatment sewage is polluted with different compounds that...

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!