The presence and activity of Desulfotomaculum spp in sulphate-limited freshwater sediments

Abstract Addition of pyrophosphate stimulated sulphate uptake and utilization of volatile fatty acids by anaerobic freshwater sediments. Population estimates of sulphate-reducing bacteria demonstrated that a larger number were capable of utilizing acetate then lactate. Estimates increased when pyrophosphate was added to the medium and decreased by the same degree when the sediment was heated. Addition of molybdate to the sulphate-limited sediments stimulated rather than inhibited methanogenesis. The results suggest that the sediment contains a metabolically active population of acetate-utilizing members of the genus Desulfotomaculum .