Microbiology Module 12.1

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Microbial Ecology
- Study of interactions of microbes with their environments
- 10 to the 30th microbes on earth
- Microbes are metabolically active and have major changes on environment
- Control the relatively hi levels of O2 and lo levels of N2 and CO2
Studying Microbes in the Lab
- Difficult to study microbes in lab
- Much less than 1% of microbes can be cultured in lab
- Difficult to find enrichment cultures
- Caution: Culturing microbes under lab conditions often changes phenotypes overtime.
- Many microbes only grown in communities along other species
Modern Approaches to the Study of Microbial Ecology
- FISH (fluorescence in situ hybridization): Identify microbes using NA probes tagged w/fluorescent dyes
- Immunofluorescence Microscopy: Does same thing as FISH but uses a tagged antibody instead of NA
- FACS (fluorescence activated cell sorter): Sort live cells to be grown after being sorted using tagged antibodies. Cells are spit thru narrow FACS channel
- PCR
- Micro-autoradiography: Cells are kept alive in a culture (metabolically active). Used to study metabolic pathways
Carbon Cycle
- 1. CO2 fixed by Autotrophs: CO2 + H2O --> CH2O + O2. (Can be fixed aerobically or anaerobically)
- 2. Fixed carbon degraded to CO2 and CO2 is reduced to CH4 by methanogens
- 3. CH4 is oxidized to CO2 by methanotrophs
Greenhouse Gases
- CO2 and CH4 both greenhouse gases
- Allows all of radiation from the sun to go thru atmosphere, but do not infrared heat to escape earth
- CO2 levels very small in atmosphere (730Gt) vs. 1.1 million Gt of O2
- CO2 consumed and trapped by autotrophs & in CaCO3 shells
- CH4 8-20X more potent than CO2
- Take more CO2 out of atmosphere than is returned yearly
Carbon Reservoirs
- Most carbon on earth is stored in rocks (99.5%). Slowly released
- Large amounts of methane trapped in hydrates (ice). Produced by methanogens
- Environmentalists fear that large release of C4 may cause more global warming
Oxycyle
- In balance and cannot be easily perturbed
- Very large reservoir (1.1 million Gt)
- Biological processes (respiration) balanced by noncyclic photophosporylation
Nitrogen Cycle
- Nitrogen Fixing: Reduction of N2 into NH4
- Ammonification (mineralization): N--> NH4+
- Nitrification: NH4+ --> NO3-
- Denitrification: NO3- --> N2
- Anmmox NO2- + NH3 --> 2N2
Sulfur Cycle
- Very Complicated
- Do not have to know various organisms and their reactions
- Sulfur metabolizers can offset global warming. Sulfuric acid can prevent sunlight from reaching the earth
Phosphorus Cycle
- No gaseous components
- No Redox chemistry
- Very stable: Only used to form hi energy phosphate bonds thru dehydration
- no transfer of electrons
- Phosphate can cycle between soluble and insoluble forms

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Marcusje3

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Microbiology Module 12.1

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Module 12.1

Updated

2010-11-03T04:28:44Z

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