Flavobacterium ichthyis sp. nov., isolated from a fish pond.

Bacterial strain NST-5T, isolated from a fish pond in Taiwan, was characterized using a polyphasic taxonomy approach. Results of phylogenetic analyses based on 16S rRNA gene sequences and coding sequences of 92 protein clusters indicated that strain NST-5T formed a phylogenetic lineage in the genus Flavobacterium. Analysis of 16S rRNA gene sequences showed that strain NST-5T showed the highest similarity to Flavobacterium enshiense DK69T (94.9 %), Flavobacterium ahnfeltiae 10Alg 130T (94.8 %) and Flavobacterium vireti THG-SM1T (94.8 %). Strain NST-5T showed 68.9-72.5% average nucleotide identity and 19.1-23.7% digital DNA-DNA hybridization identity with the type strains of other close related Flavobacterium species. Cells of the strain were Gram-stain-negative, strictly aerobic, motile by gliding, rod-shaped and formed yellow colonies. Optimal growth occurred at 30 °C, pH 7 and with 0.5% NaCl. Strain NST-5T contained iso-C15:0, C15:0 and iso-C16:0 as the predominant fatty acids. The major hydroxyl fatty acids were iso-C16:0 3-OH and iso-C17:0 3-OH. The polar lipid profile consisted of phosphatidylethanolamine, three uncharacterized aminophospholipids, two uncharacterized phospholipids and one uncharacterized aminolipid. The major polyamine was homospermidine. The major isoprenoid quinone was MK-6. The DNA G+C content of the genomic DNA was 35.5 mol%. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain NST-5T should be classified as a novel species of the genus Flavobacterium, for which the name Flavobacterium ichthyis sp. nov. is proposed. The type strain is NST-5T (=BCRC 81198T=LMG 31341T).