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Abstract
A Gram-negative, non-motile, psychrotolerant bacterium exhibiting high catalase activity, designated strain T-3-2T, 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 °C and in the presence of 0–12 % NaCl. The predominant isoprenoid quinone was ubiquinone-8 (Q-8), and C16 : 1 ω9c and C18 : 1 ω9c were the predominant cellular fatty acids. The DNA G+C content of strain T-3-2T was 43.9 mol%. 16S rRNA gene sequence phylogeny suggested that strain T-3-2T 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-3-2T (=JCM 15603T =NCIMB 14510T).
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