Conversion of glucose to fatty acids and methane: roles of two mycoplasmal agents.

Two species of obligately anaerobic mycoplasmas were the major components of a methanogenic glucose-limited enrichment culture. In pure culture, one of these organisms, tentatively named Anaeroplasma sp. strain London, was shown to be responsible for the fermentation of glucose to fatty acids, hydrogen, and carbon dioxide; the other mycoplasma was shown to produce methane from hydrogen and carbon dioxide and was named Methanoplasma elizabethii. This same methanogenic mycoplasma contained a low-molecular-weight fluorescent cofactor which had a maximum light absorbance at 430 nm. When both species of mycoplasmas were grown together on glucose, fermentation products included fatty acids and methane. For the first time, mycoplasmas are implicated as agents of anaerobic degradation and methanogenesis in a sewage sludge digester.