Flavobacterium tilapiae sp. nov., isolated from a freshwater pond, and emended descriptions of Flavobacterium defluvii and Flavobacterium johnsoniae.

A bacterial strain, designated Ruye-71(T), was isolated from a freshwater tilapiine cichlid fish culture pond in Taiwan and characterized in a taxonomic study using a polyphasic approach. Cells of strain Ruye-71(T) were Gram-stain-negative, strictly aerobic, yellow-pigmented rods that were motile by gliding. Growth occurred at 10-30 °C (optimum, 15-30 °C), at pH 7.0-8.0 (optimum, pH 8.0) and with 0-2 % NaCl (optimum, 0-1 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain Ruye-71(T) belonged to the genus Flavobacterium and was most closely related to Flavobacterium defluvii EMB117(T), with a 16S rRNA gene sequence similarity of 97.7 %. Strain Ruye-71(T) contained iso-C15 : 0, summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c), C16 : 0, C16 : 0 3-OH, iso-C15 : 0 3-OH and iso-C17 : 0 3-OH as major fatty acids. The major isoprenoid quinone was MK-6. The polar lipid profile consisted of phosphatidylethanolamine and several unidentified polar lipids. The DNA G+C content of the genomic DNA of strain Ruye-71(T) was 39.2 mol%. The mean level of DNA-DNA relatedness between strain Ruye-71(T) and Flavobacterium defluvii DSM 17963(T) was 39.9±1.2 %. On the basis of phylogenetic inference and phenotypic data, strain Ruye-71(T) should be classified as representing a novel species, for which the name Flavobacterium tilapiae sp. nov. is proposed. The type strain is Ruye-71(T) ( = BCRC 80262(T) = KCTC 23312(T)). Emended descriptions of Flavobacterium defluvii and Flavobacterium johnsoniae are also proposed.