SS 2008

Martin Könnekewww.icbm.de/pmbio

Microbial Ecology

Anthropogenic habitats

Anthropogenic habitats

Sewage and drinking waterWaste water treatment and water purification

Crude oil depositMicrobial degradation of hydrocarbons

Ore depositMicrobial leaching of metals

Hygienic und safe water supply is the essentialrequirement 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 nationaldrinking water regulation

Controlled and analyzed by independent institutions

Next to microbial analysis, physical and chemicalregulations

Water hardness: depend on amount of calcium- undmagnesium compounds (earthy alkali compounds)

Drinking water should be 5-25˚dH (1 ˚dH = 10 mg/l CaO)

Coliforms as indicator organisms

Detection of coliforms indicate pollution of faeces

Phylogenetic group of Gram-negative, facultativeaerobic, non-sporeforming rods

Coliforms include typical microbes of the intestinaltract:Escherichia coli, Klebsiella pneumoniae

Coliforms in drinking water behave like manypathogenic microorganisms

Coliform colonies growing on a membrane filter

Sewage treatmentSewage is polluted with different compounds thatare not allowed to discharge into natural watersystem

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

Sewage treatment

Goals:

Elimination of pathogens

Mineralization of organic substances

Removing of N and P (limiting nutrients for primaryproducers)

Application of chemical, physical and microbiologicalmethods

Principle waste water treatment processes

Primary treatment

Flow-diagram of waste water processes with primary treatment

Discontinuous activated sludge treatment (batch-mode)

Anoxic secondary waste water treatment

Anaerobic, biological level - digestion tower

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 + MethanCO2 + Sulfid

Anaerobe Abbau von organischem Material

Sulfatreduzierer (Desulfo-) Methanogene (Methano-)

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

-

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

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

Urea

Denitrification

Nitrate -> N2

5<CH2O> + 4NO3- + 4H+ -> 5CO2 + 7H2O + N2

Nitrification

Ammonia -> Nitrate

Elimination of nitrogen

Water purification plant

Effect of water purification on the incidence

of waterborn diseases in Philadelphia

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 encodethe cholera toxin

Distribution of Cholera disease (2004)

Oil

Complex mixture of lipophiliccompounds embedded in the Earthcrust

Consist of up to 600 differentcompounds (86% hydrocarbons)

Most important energy resource andPrecursor for chemical industry

Formed by biological processes overgeological time periods (diagenesis)

Crude oil degrading microbes

Aerobic degradation: catalysed by oxygenases(fungi, Pseudomonas)

Anaerobic degradation : Fumarate addition(Sulfate- and Nitrate-reduzers

Bacteria in the oil/water-interface

Biodegradation of herbicide

Microbial processes in industrial

and environment remediation

Terrestric

CompostingLand fillRemediation of polluted soilsMicrobial leaching

Limnic & marine

Sewage treatmentDrinking water purificationRemediation of pollutions

Metal recovery by

Microbial leaching

Abb.: Spektrum der Wissenschaft;Verständliche Forschung: Industrielle Mikrobiologie, 1987

Coppermine near Salt Lake City

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.

Microbial processes during microbial leaching

Acidithiobacillus ferrooxidans oxidize metals (Cu+, Fe2+) as well assulfide

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

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isse

nsch

aft;

Indus

trie

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ikro

bio

logi

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98

7

A. thiooxidans on S0

(15 000 times)Other application:Recovery of gold and uranium