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

A novel casein hydrolysing bacterium designated strain S-52T 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-52T 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-52T formed a lineage within the genus Chitinophaga that was distinct from other species of the genus. Closest member was Chitinophaga barathri YLT18T (97.16% 16 S rRNA gene sequence similarity). The major cellular fatty acids were iso-C15:0, C16:1ω5c, iso-C17:0 3-OH, and summed feature 3 (C16:1ω7c and/or C16: 1ω6c). MK-7 was sole respiratory quinone. The major polar lipid was phosphatidylethanolamine. The DNA G + C content of strain S-52T was 48.8 mol%. DNA–DNA relatedness of strain S-52T with Chitinophaga barathri was 42.5%. On the basis of phenotypic, genotypic, phylogenetic, and chemotaxonomic characterization, S-52T represents a novel species in the genus Chitinophaga, for which the name Chitinophaga caseinilytica sp. nov. is proposed. The type strain is S-52T (= KEMB 9005-540T = KACC 19118T = NBRC 112679T).