Oceanobacillus caeni sp nov., isolated from a Bacillus-dominated wastewater treatment system in Korea

A Gram-positive, rod-shaped, spore-forming bacterium, strain S-11(T), was isolated from the activated sludge of a Bacillus-dominated wastewater treatment system in South Korea and was characterized using a polyphasic approach in order to determine its taxonomic position. Cells (0.5-0.6 x 2.0-2.2 mu m) were motile by means of a single subpolar flagellum. They bore ellipsoidal endospores that lay in a central position in swollen sporangia. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain S-11(T) was a member of the genus Oceanobacillus. 16S rRNA gene sequence similarity values and DNA-DNA relatedness of strain S-11(T) to the type strains of other Oceanobacillus species were less than 96.2 and 66.0%, respectively. Strain S-11(T) showed distinct differences in the G + C content of the genomic DNA (33.6 mol%). The major cellular fatty acids were iso-C-14:0, iso-C-15:0, anteiso-C-15:0 and iso-C-16:0. The major isoprenoid quinone was MK-7. There were also some physiological differences in comparison with the type strains of Oceanobacillus species: tests for production of acetoin and acid production from dulcitol, erythritol, myo-inositol and sorbitol were positive. The results of DNA-DNA hybridization and physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain S-11(T) from the six Oceanobacillus species and subspecies with validly published names. Strain S-11(T) therefore represents a novel species, for which the name Oceanobacillus caeni sp. nov. is proposed, with the type strain S-11(T) (=KCTC 13061(T) = CCUG 53534(T) = CIP 109363(T)).