Chitinophaga caseinilytica sp. nov., a casein hydrolysing bacterium isolated from forest soil

A novel casein hydrolysing bacterium designated strain S-52^T was isolated from Kyonggi University forest soil. Cells were strictly aerobic, Gram stain-negative, oxidase- and catalase- positive, non-motile, non-spore-forming, rod-shaped, and golden-yellow-pigmented. Strain S-52^T hydrolysed casein. It was able to grow at 20-37 °C (optimum 25-32 °C), pH 6.5-11.0 (optimum 7-9.5), and at 3% (w/v) NaCl concentration. Strain exhibits flexirubin-type pigments. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain S-52^T formed a lineage within the genus Chitinophaga that was distinct from other species of the genus. Closest member was Chitinophaga barathri YLT18^T (97.16% 16 S rRNA gene sequence similarity). The major cellular fatty acids were iso-C_15:0, C_16:1ω5c, iso-C_17:0 3-OH, and summed feature 3 (C_16:1ω7c and/or C_{16: 1}ω6c). MK-7 was sole respiratory quinone. The major polar lipid was phosphatidylethanolamine. The DNA G + C content of strain S-52^T was 48.8 mol%. DNA-DNA relatedness of strain S-52^T with Chitinophaga barathri was 42.5%. On the basis of phenotypic, genotypic, phylogenetic, and chemotaxonomic characterization, S-52^T represents a novel species in the genus Chitinophaga, for which the name Chitinophaga caseinilytica sp. nov. is proposed. The type strain is S-52^T (= KEMB 9005-540^T = KACC 19118^T = NBRC 112679^T).