Purple sulfur bacteria are

A) alphaproteobacteria that oxidize hydrogen sulfide in the presence of oxygen or nitrate.
B) gammaproteobacteria that use hydrogen sulfide as an electron donor for photosynthesis.
C) a phylogenetically heterogeneous group of microbes that reduce sulfate to sulfur.
D) thermophilic bacteria that reduce elemental sulfur to sulfide.


Answer: B

Biology & Microbiology

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