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)).The authors thank Ms Moon Eun Young and Dr Jongsik Chun for technical assistance. Thanks are also due to Professor Byung CheolCho (Seoul National University) for the gift of the type strain of Oceanobacillus profundus. This research was supported by a grant (code no. I 2WATERTECH 04-7) from I 2WaterTech of Eco-STAR project funded by Ministry of Environment, Korea