BIOLOGY 2EE3 Lecture Notes - Lecture 3: Bioaugmentation, Basidiomycota, Eutrophication

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12 Aug 2016
Department
Biogeochemical Cycles 14:27
Biogeochemical Cycles Link Metabolic Processes of Organisms for production
of degradation of biomass
Cycling of Elements
All Biomass consists of biogenic elements in roughly similar proportions (C,
O, N, H, P, K)
Often involves change in oxidation state (organisms contribute via redox
reactions)
Elements are contained in reservoirs (Terestrial, Aquatic, Atmosphere)
Flux is the movement of elements between reservoirs (eventually reach
equilibrium)
Human activities threaten to disrupt this equilibrium
Monitoring Chemical Cycling
Detecting Atmospheric Gasses
Air Collected in a sealed cylinder is subjected to infrared radiation
If More is absorbed (not detected), more CO2 is present
Use of mesocosms (artificially enclose ecosystems) can measure change
over time
Radioisotope Tracers
Molecules are labeled with radioactive elements prior to release in mesocosm
Determination of the movement of the radioactively labeled elements
through the mesocosm can inform researchers on cycling methods
The global carbon cycle
A balance is maintained between organic and inorganic carbon reservoirs
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Complementary metabolic activities of photosynthesis, respiration and
decomposition maintain the balance
Human activity can disrupt these cycles inc atmospheric levels of
greenhouse gasses
Photosynthesis, Respiration and Decomposition
if CO2 fixation exceeds respiration, organic matter accumulated
Positive net community productivity
Fermentation processes produce partially oxidized organic end products
These can erve as nutrients for other organisms
Methanogens – Production of Methane as a byproduct of biodegradation of
organic carbon in an anoxic environment
As methanogens only use a strict “diet” of substrates they rely on
communities of interdependent organisms (consortias)
Give and take these pairings = syntrophic relationship
Hydrogenotrophic methanogens produce CH4 from CO2 and H2
Acetotrophic methanogens produce CH4 from acetate (CH3COO)
Methanotrophy
Metabolism of CH4 into other forms (inc carbon cycling)
Aerobically (Dependent on methane monooxygenase (MMO)) enzyme
Archae responsible have yet to be cultured
Called Anaerobic methan oxidizers (ANME’s)
3 Distinct Phyla recognized by DNA Anal
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Anaerobically (Mostly in Marine Enviro by Archae)
Nitrogen Metabolism to Cycle
Most abundant in atmospheric reservoir (79%) unstable in N2 Form
Several Steps  Nitrogen Fixation, Nitrification, Denitrification
Fixation: N2 into NH4 by m trogenase complex
Carried out by aerobic/anaerobic bacteria and archae
Nitrification: NH4 into NO2 or NO3 via different set of microbes
Nitrite production via 2 enzyme process using (AMO)
Ammonia Monooxygenase and Hydroxylamine Oxidoreductase
Nitrifiers take the reactions 1 step further using nitrite and nitrate
oxidoreductase (NOR) to produce nitrate
Denitrification
Use of nitrate/nitrate as terminal electron acceptor
Eventually producing N2
Human Impact on Nitrogen Cycle
Haber Bosch Process can produce synthetic nitrogen fertilizer
Overuse of fertilizers contributes to marine dead cores
Imbalances of nitrogen Reservoirs and ecosystems
Cycling of Oxygen
Actively Cycled reservoirs of O2 include O2, CO2, H2O
Heavily cycled back and forth between photosynthesis and respiration
reactions
Can be used marginally in anaerobic respiration (SO4 as terminal electron
acceptor)
Connections between various cycles is common
Cycling of Sulfur and Phosphorous
Mostly found in rocks and dissolved H2O
Incorportated via terrestrial and aquatic microrg into higher order organisms
Decomp reactions release elements back to terr and aqua sys to complete
cycling
Microbes are criticial to these processes as some can metabolize inorg
molecules containing the elements
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