Flavobacterium commune sp. nov., isolated from freshwater and emended description of Flavobacterium seoulense.

A Gram-stain-negative, yellow, facultatively-anaerobic, short, rod-shaped, non-spore-forming bacterium, designated PK15T, was isolated from freshwater. Growth was observed at 4-40 °C (optimum, 30 °C), pH 6-9 (optimum, 8), and in the presence of 0-0.8 % (w/v) NaCl (optimum, 0.4 %). Strain PK15T exhibited both catalase and oxidase activities and was able to reduce nitrate. On the basis of 16S rRNA gene sequence similarities, strain PK15T was shown to belong to the genus Flavobacterium with close similarities to Flavobacterium palustre S44T (97.9 %) and Flavobacterium seoulense EM1321T (97.7 %). Menaquinone-6 (MK-6) was the major respiratory quinone, while the G+C content of the genomic DNA was 35.5 (±0.9) mol%. The major polar lipids were phosphatidylethanolamine, three unidentified aminolipids, one unidentified aminophospholipid and three unidentified polar lipids. The predominant cellular fatty acids (≥10 %) were anteiso-C15 : 0 (17.3 %), a summed feature comprising C16 : 1ω7c and/or C16 : 1ω6c (15.1 %) and iso-C15 : 0 (10.0 %). Chemotaxonomic data supported the affiliation of strain PK15T to the genus Flavobacterium. The results of physiological and biochemical tests allowed genotypic and phenotypic differentiation of strain PK15T from strains of closely related species. It was, therefore, evident that PK15T represents a novel species of the genus Flavobacterium, for which the name Flavobacterium commune sp. nov. is proposed with strain PK15T (=KCTC 52562T=JCM 32115T) as the type strain. Based on the results of the chemotaxonomic characterization in the present study, an emended description of Flavobacterium seoulense is also proposed.