Any of various groups of unrelated bacteria that utilize sulphur, sulphide, or sulphate in their metabolism. The anaerobic photoautotrophic green sulphur bacteria and purple sulphur bacteria can use hydrogen sulphide as a source of electrons in photosynthesis, producing sulphur as a by-product:
2H2S + CO2 → H2O + CH2O + 2S
The chemoautotrophic sulphur-oxidizing bacteria, such as Thiobacillus, derive energy from the oxidation of sulphur or its compounds (e.g. sulphide), producing sulphate (SO42−). The anaerobic heterotrophic sulphate-reducing bacteria, such as Desulfovibrio, require sulphate for respiration, deriving energy from its reduction to sulphur or hydrogen sulphide. The aerobic filamentous sulphur bacteria (e.g. Beggiatoa), which belong to the phylum Myxobacteria (gliding bacteria), can grow by oxidizing sulphides to sulphates.
Subjects: Biological Sciences.