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

Abstract.

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 (C₂–C₅), 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 CO₂, 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 °C and 30 °C with an optimum at 25 °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-16:1ω7, n-16:1 ω5, n-17:1 ω6 and n-18:1 ω7 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.