Psychrobacter piscatorii sp. nov., a psychrotolerant bacterium exhibiting high catalase activity isolated from an oxidative environment.

A Gram-negative, non-motile, psychrotolerant bacterium exhibiting high catalase activity, designated strain T-3-2(T), was isolated from a drain of a fish-processing plant. Its catalase activity was 12 000 U (mg protein)(-1), much higher than the activity of the other Psychrobacter strains tested. The strain grew at 0-30 degrees C and in the presence of 0-12 % NaCl. The predominant isoprenoid quinone was ubiquinone-8 (Q-8), and C(16 : 1)omega9c and C(18 : 1)omega9c were the predominant cellular fatty acids. The DNA G+C content of strain T-3-2(T) was 43.9 mol%. 16S rRNA gene sequence phylogeny suggested that strain T-3-2(T) is a member of the genus Psychrobacter, with the closest relatives being the type strains of Psychrobacter nivimaris (99.2 % similarity), P. aquimaris (98.7 %) and P. proteolyticus (98.5 %). DNA-DNA hybridization showed less than 65 % relatedness with these strains. A phylogenetic tree based on gyrB gene sequences was more reliable, with higher bootstrap values than the 16S rRNA gene sequence-based tree. The result also differentiated the isolate from previously reported Psychrobacter species. Owing to the significant differences in phenotypic and chemotaxonomic characteristics and the phylogenetic and DNA-DNA relatedness data, the isolate merits classification within a novel species, for which the name Psychrobacter piscatorii sp. nov. is proposed. The type strain is T-3-2(T) (=JCM 15603(T) =NCIMB 14510(T)).