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38 Cards in this Set

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  • Back
Nitrous oxide
200X more potent greenhouse gas than carbon dioxide; 150 yr residence in atmosphere. Generated by burning of fossil fuels.
Nitric oxide
depletes ozone layer and causes smog
Powerful oxidant, irreversibly binds heme (is a toxin). Transient in environment.
Produced by Haber Bosch. Easy to leach out of soil.
Ammonia (NH3)
positively charged and binds to negatively charged clay colloids in soils. Not leached
– biological nitrogenous waste, made from carbon dioxide, water ammonia, aspartate. Ammonia is toxic, must combine to excrete.
Combined Nitrogen
nitrogen in organic molecules such as amino acids and nucleotides (does not equal fixed nitrogen)
Inorganic Nitrogen
usually refers to nitrate, ammonia, nitrite and dinitrogen gas (fixed nitrogen is part of it)
"two nitrogen eater" used to refer to bacteria that can use ('fix') N2 as sole source of nitrogen.
well nourished
The production of N2 and N20 from the reduction of nitrate or nitrite coupled to an increase in growth
What are nirK and nirS used for?
Screening environmnets for denitrification genetic potential
Where does denitrification occur?
anaerobic to semi-aerobic environment
What is the terminal electron acceptor in a denitrification reaction?
When does denitrification occur?
When oxygen concentrations are low ie water saturated soils
What are the two reactions of Chemolithoautotrophs? Ex. Thioploca sp.
HS- to SO4-2
NO3- to NH4+ or N2
Where does nitrification take place?
Periplasm of Gram - bacteria
thought to be a redox sink to dispose of excess reducing equivalents since does not involve proton translocation
a high affinity nitrite reductase, gives competitive advantage when nitrate/nitrite concentrations low in enviroment
assimilatory nitrite reductase in enterobacteria
What do products like Hagen Cycle Water Treatment or Stress Zyme for fish tanks do?
Remove ammonia (NH3)and nitrite (NO2-) with the addition of microorganisms
Is nitrification aerobic or anaerobic?
What are the disadvantages of nitrification?
slow growth rates and poor yields
All bacteria carrying out nitrification are chemotrophs or autotrophs?
Autotrophs - carbon comes from carbon dioxide
In products like Stresszyme for fish tanks, what is the bacteria that carries out the rxn?
complete oxidation of ammonia to nitrate requires 2 different bacteria physiologies:
Nitrosomonas (ammonia to nitrite) and nitrobactor (nitrite to nitrate)
Which is are more diverse nitrifiers or denitrifiers?
Nitrification is much less diverse than Denitrification.
How does nitrification use up oxygen and yield oxygen at the same time
The answer has to do with the link between nitrifier activity in nitrification and nitrifier acitivity in use of CO2 as an autotrophic cource of carbon which must be fixed into organic carbon (which costs energy)
carbon dioxide + ammonia + water yields oxygen and organic nitrogen carbon product
what is the only baterial biological process that allows new continued/inorganic nitrogen to enter the ecosystem
Nitrogen fixation
Where are some places that nitrogen fixation occurs?
soil, rootzone of plants, cyanobacteria, heterocysts
What form is sulfur most commonly taken up by organisms?
sulfate SO4-2
Anammox reaction
Oxidation of ammonia with the reduction of nitrite to produce N2 and water
Anammox bacteria
fix carbon dioxide as their sole carbon source
have very slow growth rate
create huge flux of N2 in marine sediment
what are the three major types of nitrogenases?
FeV nitrogenase (Vanadium)
FeFe only nitrogenase - can be up to 20% of total cellar protein
what is the only baterial biological process that allows new continued/inorganic nitrogen to enter the ecosystem
Nitrogen fixation
What are the two steps in ammonia oxidation to nitrite?
Step 1: oxidation of ammonial to hydroxylamine using ammonia momooxygenase enzyme
Step 2: oidation of hydroxylamine to nitrite with hydroxylamine monooxygenase enyzme
Ammonia is the electron donor and oxygen is the e acceptor
What is biological oxygen demand
the demand the community places on the aquatic environment to provide oxygen as an e- acceptor
Why is BOD a good assessor of environmental pollution?
Because oxygen must be present for nitrifiers in the ammonia oxidation to nitrite. More oxygen demand indicates high levels of nitrification (too much nitrogen in environment)
What is the intermediate product in ammonia oxidation to nitrate?
hydroxylamine and nitrite