which process of the sulfur cycle involves purple and green bacteria?
in progress 0Microbial ecology 3 years 2019-10-18T21:09:12+00:00 2019-10-18T21:09:12+00:00 1 Answer 344 views New Member 0
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Answer ( 1 )
These are the bacteria that can use sulfate to accept the electrons during anaerobic conditions. These are the anaerobic bacteria that reduce sulfate into hydrogen sulfide.
The characteristics of the sulfur-reducing bacteria are as follows:
Why bacteria use sulfate?
These bacteria grow in anaerobic conditions. They can’t use oxygen as electron terminal acceptor. They reduce inorganic sulfate into hydrogen sulfide. Sulfur accepts the electron from ETC. Some microbes assimilate sulfur to fulfill their sulfur requirement. They may use organic sulfur to fulfill their requirement.
SO4 SO3-2 H2S
This is done by sulfate reductase enzymes
Classification of sulfate-reducing bacteria:
These are of two types.
These are the bacteria that oxidize organic compounds such as carbohydrates, organic alcohols and acids, and aromatic hydrocarbons. They obtain electron acceptor from the oxidation organic compounds.
These bacteria use inorganic compounds for the acceptance of electron. They oxidize the molecular hydrogen and use them as the electron acceptor. They live in anaerobic conditions and compete with methanogens. They can use inorganic iron as the electron acceptor.
These bacteria can prepare their own food by photosynthesis. They can use light energy and fix the CO2 into food. They have bacterial chlorophyll that can convert light energy into glucose. They are commonly green sulfur bacteria.
These bacteria can’t prepare their own food. They use the chemical to get energy and use organic carbon for its requirement. They don’t have bacterial chlorophyll to convert light energy into glucose. They are purple sulfur bacteria.
Purple sulfur bacteria and green sulfur bacteria.
These are the group of anaerobic bacteria that are capable of photosynthesis. They may be Microaerophilic bacteria. These bacteria are divided into two groups i.e. the Chromatiaceae and the Ectothiorhodospiraceae. They are different in their internal membranes structure and presence of extracellular or intracellular sulfur granules.
The characteristics of purple sulfur bacteria are as follows.
Reduced sulfur S
These bacteria use reduce sulfur as electron donor as they can’t use oxygen. They produced hydrogen sulfide that produces rotten egg smell. They are photosynthetic in nature as they can fix the inorganic carbon into glucose. They can use light energy to get energy and fix CO2
CO2 + H2S C6H12O6 + S
They produce granules that can be observed under 1000X microscope. They give purple to pink color to the water. They grow in dark places.
They are mainly photoautotrophic that is they can synthesize or prepare its own food. But some are chemoautotrophic that they use chemical to get energy. They may be photoheterotrophic that can’t fix carbon into its food but get energy from light. They are strict anaerobic bacteria but some of them are good fermenters.
The ecological importance of purple sulfur bacteria is as:
These bacteria can reduce the harmful waste from the environment. Purple sulfur bacteria lower the amount of hydrogen sulfide, methane and toxic compound present in water lagoons.
Hydrogen sulfide use as a source of sulfur for the purple sulfur bacteria while methane use as the source of carbon for these bacteria. Thus, purple sulfur bacteria lower the odor and toxicity of water.