Desulfobotulus pelophilus sp. nov., an Alkaliphilic Sulfate-Reducing Bacterium from a Terrestrial Mud Volcano

Abstract

—An alkaliphilic, sulfate-reducing, anaerobic bacterium (strain H1T) was isolated from a terrestrial mud volcano at the Taman Peninsula, Russia. The cells of the isolate were gram-negative motile vibrios, 1 µm in diameter and 2.0–2.5 µm in length. Strain H1T grew at 14–42°C (optimum at 37°C), pH 8.5–10.5 (optimum at pH 9.5), and NaCl concentrations of 0.5–6% (wt/vol) (optimum at 0.5–1.5%); pyruvate, lactate, butyrate, caproate, or pelargonate were used as electron donors, and elemental sulfur, sulfite, or sulfate were used as electron acceptors. Pyruvate and lactate were fermented. No growth occurred in the presence of oxygen. Thiosulfate, DMSO, fumarate, nitrate, nitrite, arsenate, selenite, and Fe(III) were not used as electron acceptors. Elemental sulfur, thiosulfate, and sulfite were not disproportionated. Glucose, fructose, sucrose, trehalose, galactose, xylose, fumarate, citrate, yeast extract, and peptone were not fermented. Predominant fatty acids were C20:0 (54.2%), C22:0 (24.6%), and C18:0 (11.1%). The genome of strain H1T was 3.66 Mb in size and had G + C DNA content of 51.1%. The genome contained the genes encoding the enzymes of dissimilatory sulfate reduction and β-oxidation of fatty acids. According to the results of analysis of the 16S rRNA gene sequence, Desulfobotulus mexicanus was the organism most closely related to strain Н1Т (98.3% similarity). Based on its phenotypic characteristics and the data of phylogenetic analysis, affiliation of the isolate as member of a novel Desulfobotulus species, Desulfobotulus pelophilus sp. nov., is proposed, with the type strain H1T (=DSM 112796T = VKM B-3697Т =UQM 41590T).