Microbiology Module 12.1

  1. 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
  2. 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
  3. 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
  4. 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
  5. 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
  6. 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
  7. Oxycyle
    • In balance and cannot be easily perturbed
    • Very large reservoir (1.1 million Gt)
    • Biological processes (respiration) balanced by noncyclic photophosporylation
  8. Nitrogen Cycle
    • Nitrogen Fixing: Reduction of N2 into NH4
    • Ammonification (mineralization): N--> NH4+
    • Nitrification: NH4+ --> NO3-
    • Denitrification: NO3- --> N2
    • Anmmox NO2- + NH3 --> 2N2
  9. 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
  10. 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
Card Set
Microbiology Module 12.1
Module 12.1