Proposal of Desulfosarcina ovata subsp. sediminis subsp. nov., a novel toluene-degrading sulfate-reducing bacterium isolated from tidal flat sediment of Tokyo Bay.

Strain 28bB2T is a sulfate-reducing bacterium isolated in a previous study, obtained from a p-xylene-degrading enrichment culture. Physiological, phylogenetic and genomic characterizations of strain 28bB2T were performed to establish the taxonomic status of the strain. Cells of strain 28bB2T were short oval-shaped (0.8-1.2×1.2-2.7μm), motile, and Gram-negative. For growth, the optimum pH was pH 6.5-7.0 and the optimum temperature was 28-32°C. Strain 28bB2T oxidized toluene but could not utilize p-xylene. Sulfate and thiosulfate were used as electron acceptors. The G+C content of the genomic DNA was 53.8mol%. The genome consisted of an approximately 8.3 Mb of chromosome and two extrachromosomal elements. On the basis of 16S rRNA gene analysis, strain 28bB2T was revealed to belong to the genus Desulfosarcina, with high sequence identities to Desulfosarcina ovata oXyS1 (99.5%) and Desulfosarcina cetonica DSM 7267 (98.7%). Results of Average Nucleotide Identity (ANI) calculation and digital DNA-DNA hybridization (dDDH) analysis showed that the strain 28bB2T should be classified as a subspecies under D. ovata. Based on physiological and phylogenetic data, strain 28bB2T (=NBRC 106234 =DSM 23484) is proposed as the type strain of a novel species in genus Desulfosarcina, Desulfosarcina ovata subsp. sediminis subsp. nov.