MC7: Microbial geochemical cycling Flashcards
What are biogeochemical cycles?
A pathway by which a chemical substance moves through biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth
Give examples of biotic and abiotic factors
Biotic: predators, decomposers
Abiotic: air, water, minerals
Define ‘reservoir’, including the terms ‘source’ and ‘sink’.
A part of the biosphere that contains significant amounts of an element. It acts as both a source for that element for living organisms and as a sink to which it returns.
List the major processes that occur in the microbial-driven carboin cycle
- Oxygenic photosynthesis
- Aerobic respiration
- Anaerobic respiratioin
- Fermentation
- Anoxygenic photosynthesis
- Acetogenesis
- Methanogenesis
- Methanotrophy
Describe the aerobic carbon cycle
-
Photosynthesis fixes CO2 into biomass
- This produces O2 and organic compounds
- Lithotrophs also reduce CO2 to biomass
-
Respiration returns CO2 to the atmosphere
- There is a net gain of O2/loss of CO2 in photic zone
Describe the anaerobic carbon cycle
- Has lower cyclling rate than aerobic cycles
- Less iron and less redox potential than O2
- Occurs in the subsurface of the environment
- e.g. soil, benthos, rock
- Involves fermentation and lithotrophic (chemoautotrophic) respiration
- Incomplete breakdown of biomass carbon
- Formation of peat, oil, gas
Give an example of a microbe that undergoes oxygenic photosynthesis
Cyanobacteria
(Martha’s fave – don’t forget it!)
Give an example of a microbe that undergoes chemoautotrophy
- Thiobacillus*
- Leptospirillum*
Give an example of a microbe that undergoes methanotrophy
- Methylococcus*
- Methylosinus*
Give an example of a microbe that undergoes acetogenesis
Clostridium acetobutylicum
Give an example of a microbe that undergoes anoxygenic photosynthesis
Heliobacteria
Give an example of a microbe that undergoes anaerobic respiration
Yeast
Give an example of a microbe that undergoes fermentation
Yeast
List the major processes in the nitrogen cycle
- Nitrification
- Nitrogen fixation
- Denitrification
- Assimilation
- Ammonification
- Anaerobic ammonium oxidation (anammox)
Give an example of a microbe that undergoes nitrogen fixation
- Klebsiella (in soil)
- Clostridium (in soil)
- Pseudomonas (in soil)
- Rhizobium (within legumes – symbiotic relationship)
- Cyanobacteria (in oceans and freshwater)
Give a brief overview of the carbon cycle
Give a brief overview of the nitrogen cycle
