Lecture 3 Whyte Flashcards
Name an example of an organic pollutant:
hydrocarbon (C-H bonds)
Name an inorganic pollutant:
mercury/metals/heavy metals
Why are most organic pollutant better degraded aerobically?
Because the process is faster and more complete oxidation to CO2. This is important for bioremediation because you’re reducing the amount of contaminant in the environment more quickly, therefore it becomes less toxic
T or F: Anaerobic degradation steps are also very important in the biodegradation of some pollutants
T
T or F: Pollutant biodegradation is not limited by O2 as long as there is an alternative terminal electron acceptor and lots of it!
T
What are some examples of anaerobic systems within out bodies:
- muscles
- GI tract
What bacteria can function well in an anaerobic environement:
- SRB
- methanogens
Why is the middle of a soil aggregate anaerobic?
Because the bugs in the middle are metabolizing all the available oxygen faster than the rate of diffusion in the soil aggregate
The soil environment is a ______________ microbial habitat!
heterogenous
The soil contains both ____________ and ___________ zones, varies greatly, even within a soil aggregate
aerobic
anaerobic
T or F: O2 concentration decreases with depth in a soil
T
O2 concentration decreases towards the center of a soil particle due to diffusion, and utilization of O2 on the _________ (before it can diffuse in)
surface
Different terminal electron acceptors are available in different ______ and the availability of the terminal electron acceptors differs with ______
niches
depth
Many organisms utilize metallic terminal electron acceptors (ie., ________________________), which also vary with depth
MnO2
Fe(OH)3
T or F: Some organisms may only be able to utilize one compound as their electron acceptor whereas others may be able to utilize more than one, but usually from adjacent zones only
T
What is anaerobic respiration?
When electrons are transferred to compounds other than O2
Give the name of these 2 compounds:
- NO3
- SO4
- nitrate
- sulfate
Reduction of the terminal electron acceptor may occur in _________ rather than cytoplasm but the effect is the same
periplasm
Some organic compounds may serve as terminal electron acceptors in anaerobic respiration such as:
- fumarate to succinate via fumarate reductase
- transfer of electrons to CO2 yielding waste (CH4)
Electron donor is the one that gets _______________
oxidized
Denitrifiers use _____ as a terminal electron acceptor and reduce it to gaseous product such as _____ and ___.
NO3-
N2O
N2
A great variety of bacteria are denitrifiers. The most abundant in soil are _________ and ___________
Pseudomonas
Alcaligenes
__________________ and _________________ are toluene degrading bacteria under anaerobic conditions
Thauera aromatica
Azoarcus tolulyticus
Iron-reducing and manganese-reducing bacteria are little known bacteria that can use iron or manganese as terminal electron acceptor in the oxidation process of ______________
organic matter
A Fe-reducing bacterium degrading toluene under anoxic conditions was recently isolated:
Geobacter metallireducens GS15
H2S (hydrogen sulfide) smells like:
rotten eggs
________________ use sulfate as the terminal electron acceptor and are very useful in biodegradation/bioremediation of wastewater treatment plant
sulfate-reducing bacteria
T or F: sulfate-reducing bacteria are strict anaerobes and use sulfate as terminal electron acceptor
T
_________________ are strict anaerobes that use CO2 as electron acceptor with H2 as energy and electron source or ferment acetate. these are important bacteria for a number of environmental problems related to atmospheric trace gases, but they are also intensely studied since they have been implicated in the anaerobic degradation of toluene in sediment or activated sludge reactors
methanogenic archaea
Fermenters use ______________ as a terminal electron acceptor
organic molecules
Clostridium are a good example of _________________ found in soil
fermenting bacteria
Why is Shewanella oneidensis a super microbe:
because it can use a wide variety of electron acceptors
Mercury has tendency to concentrate in ___________________ and is highly toxic
living tissues
The major form of mercury in the atmosphere is elemental mercury (Hg0), which is volatile and oxidized to mercuric ion (Hg2+) ______________
photochemically
Most mercury enters aquatic environments as ______
Hg2+
Under anaerobic conditions, microorganisms transform Hg2+ into ____________________, an extremely soluble and toxic compound
methylmercury (CH3HG+)
T or F: Several bacteria can also transform toxic methylmercury to nontoxic forms, which is being explored to bioremediate Hg contaminated sites
T
Hg methylation is an _________________ process
anaerobic
Hg demethylation is an __________________ process
anaerobic and aerobic
T or F: Most pathogenic bacteria are heterotrophs and use organic carbon as their energy source
T
To define microbial nutritional categories we need to ask the following questions:
- What is the source of energy
- What is the source of electrons
- What is the source of carbon
Photoautotrophs get their energy source from __________ and carbon source from ________ * most cyanobacteria
light
CO2
Chemoheterotrophs get their energy and carbon source from:
organic compounds
Chemolithoatutotrophs get their energy from _______________ and their carbon from _________
- inorganic compounds
- CO2
What types of pollutants would be biodegraded by heterotrophic microorganisms?
Any type of pollutant that contains organic carbon, could probably be assimilated and biodegraded by heterotrophic microorganisms because they get their energy from carbons
Bacteria able to oxidize reduced inorganic compounds such as NH4+, H2S, or H2 to synthesize ATP for biosynthesis and fix CO2
Chemolitoautotrophs
________________ use NH4+ as sole energy source and oxiddize it to NO2-, these bacteria present some interests in the context of bioremediation since they have a monooxygenase which may attack some pollutants usch as TCE
Ammonia-oxidizing nitrfying bacteria
________________________(Nitrobacter) use NO2- as sole energy source and oxidize it to NO3-
Nitrite-oxidizing nitrifying bacteria
Environmental systems like soil or sediment are not ____________
homogenous
Do the order of the 4 best electron acceptors in marine or fresh water system overlaying sediments:
- Oxygen respiration
- NO3-
- SO4 2-
- CO2
A profile of sediment shows that after the depletion of O2, NO3- is depleted and then depletion of SO4 2- results in _________________. Finally, the utilization of CO2 results in _____________________ as ll the other potential electron acceptors have been depleted
- sulfide accumulation
- CH4 accumulation
Give an example of a reduced organic compounds
carbohydrates, CH4
Give an example of a reduced inorganic compounds
H2S, Fe2+
Need to energize the ______________________ via proton gradient
cytoplasmic membrane
Proton gradient powers the production of:
ATP, NADPH
The _______________ of NADPH are required for some biochemical reactions
reducing powers
