Characterization of carbazole degrading marine bacterium strain OC6S isolated from seawater of Kobe, Japan, a probable novel species and genus from‘Alphaproteobacteria’class

Abstract

The carbazole-degrading marine bacterium OC6ST was isolated from seawater collected off the coast of Kobe, Japan. Phylogenetic analysis of 16S rRNA revealed that this strain is distinct from other known orders of class ‘Alphaproteobacteria’. The closest related bacterium was Kordiimonas gwangyangensis GW14-5T, although 16S rRNA similarity was only 90.1%. Strain OC6ST was Gram-negative, motile, rod-shaped, catalase-positive, oxidase-positive, nitrate-reducing, and mesophilic. Respiratory quinone was Q-10 for both aerobic and anaerobic growth, and the DNA G+C content was 58.3 mol%. Optimal cell growth was observed at 16-37 °C, pH 5.5-10, and at NaCl concentrations up to 5%. The dominant fatty acids were C18 : 1 ω7c (41.54%), C14 : 0 2-OH (14.21%), and C17 : 1 ω6c (10.10%). The results suggest that this marine bacterium may be representing a novel genus and species within ‘Alphaproteobacteria’.