sp. nov., a novel sulfate-reducing bacterium isolated from the sediment of an alkaline crater lake in Mexico.

A novel Gram-negative, non-spore-forming, vibrio-shaped, anaerobic, alkaliphilic, sulfate-reducing bacterium, designated strain PAR22N, was isolated from sediment samples collected at an alkaline crater lake in Guanajuato (Mexico). Strain PAR22N grew at temperatures between 15 and 37 °C (optimum, 32 °C), at pH between pH 8.3 and 10.1 (optimum, pH 9.0-9.6), and in the presence of NaCl up to 10 %. Pyruvate, 2-methylbutyrate and fatty acids (4-18 carbon atoms) were used as electron donors in the presence of sulfate as a terminal electron acceptor and were incompletely oxidized to acetate and CO. Besides sulfate, both sulfite and elemental sulfur were also used as terminal electron acceptors and were reduced to sulfide. The predominant fatty acids were summed feature 10 (C ω7 and/or C ω9 and/or C ω12), C ω9 and C. The genome size of strain PAR22N was 3.8 Mb including 3391 predicted genes. The genomic DNA G+C content was 49.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that it belongs to the genus within the class . Its closest phylogenetic relatives are (98.4 % similarity) and (97.9 % similarity). Based on phylogenetic, phenotypic and chemotaxonomic characteristics, we propose that the isolate represents a novel species of the genus with the name sp. nov. The type strain is PAR22N (=DSM 105758=JCM 32146).