Desulfobulbus mediterraneus sp. nov., a sulfate-reducing bacterium growing on mono- and disaccharides

A new sulfate-reducing bacterium, strain 86FS1, was isolated from a deep-sea sediment in the western Mediterranean Sea with sodium lactate as electron and carbon source. Cells were ovoid, gram-negative and motile. Strain 86FS1 contained b- and c-type cytochromes. The organism was able to utilize propionate, pyruvate, lactate, succinate, fumarate, malate, alanine, primary alcohols (C(2)-C(5)), and mono- and disaccharides (glucose, fructose, galactose, ribose, sucrose, cellobiose, lactose) as electron donors for the reduction of sulfate, sulfite or thiosulfate. The major products of carbon metabolism were acetate and CO(2), with exception of n-butanol and n-pentanol, which were oxidized only to the corresponding fatty acids. The growth yield with sulfate and glucose or lactate was 8.3 and 15 g dry mass, respectively, per mol sulfate. The temperature limits for growth were 10 degrees C and 30 degrees C with an optimum at 25 degrees C. Growth was observed at salinities ranging from 10 to 70 g NaCl l(-1). Sulfide concentrations above 4 mmol l(-1) inhibited growth. The fatty acid pattern of strain 86FS1 resembled that of Desulfobulbus propionicus with n-14:0, n-16:1omega7, n-16:1 omega5, n-17:1 omega6 and n-18:1 omega7 as dominant fatty acids. On the basis of its phylogenetic position and its phenotypic properties, strain 86FS1 affiliates with the genus Desulfobulbus and is described as a new species, Desulfobulbus mediterraneus sp. nov.