Oceanobacillus oncorhynchi sp. nov., a halotolerant obligate alkaliphile isolated from the skin of a rainbow trout (Oncorhynchus mykiss), and emended description of the genus Oceanobacillus

Abstract

A halotolerant, obligately alkaliphilic bacterium, R-2T, was isolated from the skin of a rainbow trout (Oncorhynchus mykiss), a freshwater fish. The strain is Gram-positive, ferments several carbohydrates, is rod-shaped and motile by peritrichous flagella and produces ellipsoidal spores. The isolate grows at pH 9–10 but not at pH 7–8. This micro-organism grows in 0–22 % (w/v) NaCl at pH 10. Its major cellular fatty acids are iso-C15 : 0, anteiso-C15 : 0 and anteiso-C17 : 0, the major isoprenoid quinone is MK-7 and the DNA G+C content is 38·5 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicates that strain R-2T is a member of the genus Oceanobacillus. DNA–DNA hybridization reveals low relatedness between the isolate and Oceanobacillus iheyensis (21·0 %). On the basis of phenotypic characteristics, phylogenetic data and DNA–DNA relatedness data, the isolate should be designated as a novel species, for which the name Oceanobacillus oncorhynchi sp. nov. is proposed. The type strain is R-2T (=JCM 12661T=NCIMB 14022T).