Paraffinic hydrocarbons in the sulfate-reducing bacterium Desulfovibrio desulfuricans

Lipid extracted from the anaerobic, sulfate-reducing bacterium, Desulfovibrio desulfuricans, constitutes 5-9 percent of the cellular weight. About 25 percent of the lipid consists of saturated hydrocarbons. A prominent series of normal paraffins (C25-C35)in the saturated hydrocarbon fraction show no particular preference for odd- or even-numbered carbon chains. Fatty acids of the cellular lipid are of shorter chain length and include palmitic (C16), stearic (C18)and oleic (C18), common fat components. There is thus no obvious precursor-product relationship between the fatty acids and the paraffins. In the sedimentary environment bacterial synthesis of hydrocarbons and other products may be of particular significance. Being last in the food chain, bacteria ultimately become the only organisms with biosynthetic capability and thus would be expected to effect organic matter modification as long as biospheric conditions exist. Theoretically, the effect is expected to increase with depth of sediments as the pattern of prior plant and animal synthesis is gradually displaced or'superimposed by bacterial synthesis.