Cellular fatty acid composition of 8 species of sulfate-reducing bacteria was determined.
Five species of Desulfovibrio, non-sporulating sulfate-reducing bacteria, were divided into two major groups based on the composition. One group contained unsaturated branched-chain fatty acids as major fatty acids and the other did not. Desulfovibrio vulgaris, Desulfovibrio desulfricans, and Desulfovibrio salexigens in the former group contained iso-C_15:0, C_16:0, and iso-C_17:1 as the most abundant acids. In Desulfovibrio africanus which was also classified into the former group, the relative amount of each acid was largely different from that in the 3 species mentioned above. The most abundant acid was C_18:1^Δ11 and iso-C_16:1, iso-C_17:1, and anteiso-C_17:1 were detected as the next most abundant acids. In contrast, Desulfovibrio gigas which belonged to the latter group contained anteiso-C_15:0 and iso-C_14:0 as major acids and the overall profile of the composition was remarkably different from the 4 species in the former group.
The cellular fatty acid composition in 3 species of Desulfotomaculum, sporulating sulfate-reducing bacteria, was different from that in the Desulfovibrio species. The 3 species were divided into two major groups. Desulfotomaculum nigrificans contained odd-numbered saturated branched-chain fatty acids (iso-C_15:0 and anteiso-C_15:0) as major acids, and in Desulfotomaculum orientis and Desulfotomaculum ruminis, even numbered straight-chain fatty acids (C_16:0 and C_16:1) were the major acids.
Heterogeneity in the cellular fatty acid composition in both of non-sporulating and sporulating species suggests taxonomical confusion in the sulfate-reducing bacteria.