Bacterial strain NST-14T, isolated from a freshwater fish pond in Taiwan, was characterized using a polyphasic taxonomy approach. The strain was Gram-stain-negative, strictly aerobic, non-motile, rod-shaped and formed pink colonies. Optimal growth occurred at 30 °C, pH 7 and in the absence of NaCl. Phylogenetic analyses based on 16S rRNA gene sequences and coding sequences of 92 protein clusters indicated that strain NST-14T formed a phylogenetic lineage in the genus Hymenobacter. Analysis of 16S rRNA gene sequences showed that strain NST-14T had the highest similarity to Hymenobacter actinosclerus CCUG 39621T (97.7%), Hymenobacter amundsenii P5136T (97.3%) and Hymenobacter humicola P6312T (96.9%). Strain NST-14T showed 75.1-85.3 % average nucleotide identity, 73.7-89.8 % average amino acid identity and 14.5-26.0 % digital DNA-DNA hybridization with the type strains of other closely related Hymenobacter species. Strain NST-14T contained iso-C15 : 0, C16 : 1 ω5c and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) as the predominant fatty acids. The major hydroxyl fatty acids were iso-C17 : 0 3-OH and iso-C15 : 0 3-OH. The polar lipids were phosphatidylethanolamine, one unidentified glycolipid, four unidentified aminophospholipids, one unidentified aminolipid, two unidentified phospholipids and three unidentified lipids. The major polyamine was homospermidine. The major isoprenoid quinone was MK-7. The DNA G+C content of the genomic DNA was 62.4 mol%. Differential phenotypic properties, together with the phylogenetic inference, demonstrate that strain NST-14T should be classified as a novel species of the genus Hymenobacter, for which the name Hymenobacter piscis sp. nov. is proposed. The type strain is NST-14T (=BCRC 81249T=LMG 31686T).
Keywords: Bacteroidetes; Cytophagales; Cytophagia; Hymenobacter piscis sp. nov.; Hymenobacteraceae.