Dissimilatory sulfate reduction
The term "dissimilatory" is used when hydrogen sulfide (H2S) is produced in an anaerobic respiration process.
By contrast, the term "assimilatory" would be used in relation to the biosynthesis of organosulfur compounds, even though hydrogen sulfide may be an intermediate.
Dissimilatory sulfate reduction occurs in four steps:[1] Which requires the consumption of a single ATP molecule and the input of 8 electrons (eā).
[2][3] The protein complexes responsible for these chemical conversions ā Sat, Apr and Dsr ā are found in all currently known organisms that perform dissimilatory sulfate reduction.
[4] Energetically, sulfate is a poor electron acceptor for microorganisms as the sulfate-sulfite redox couple has a standard formal reduction potential (E0') of -516 mV, which is too negative to allow reduction by NADH or ferrodoxin that are the primary intracellular electron mediators.
