Crenotalea thermophila gen. nov., sp. nov., a member of the family Chitinophagaceae isolated from a hot spring.

A thermophilic aerobic bacterium designated strain STH-1-Y1(T) was isolated from sulfur-turf in a Japanese hot spring (Okuhodaka hot spring, Gifu Pref.). Colonies of strain STH-1-Y1(T) were yellow and low convex morphology with a slightly irregular fringe. Cells were slender long rods, 0.4-0.6 µm wide and 1.2-3.0 µm long. The isolate was an obligate aerophilic organism, and could not grow by fermentation or nitrate respiration. The isolate had a thermophilic trait, and could grow at 35-60 °C and pH 5.5-7.5; maximum growth occurred at 55 °C and pH 7.0 with a doubling time of 1.9 h. The Biolog and API tests suggested that strain STH-1-Y1(T) was able to use various sugars such as glucose, lactose, mannose, maltose, trehalose, cellobiose and sucrose, but could not use sugar alcohols other than glycerol, i.e. adonitol, arabitol, erythritol, inositol, mannitol, sorbitol and xylitol. Lactate and glutamate could be used, but other fatty acids, i.e. acetate, citrate, propionate and succinate could not. Gelatin, casein, starch and glycogen were hydrolysed, but neither chitin nor agar was degraded. Cells lacked flexirubin and showed oxidase and catalase activities. The major respiratory quinone was menaquinone-7 (MK-7), and major cellular fatty acids were iso-C15 : 0, iso-C17 : 0 3-OH, iso-C17 : 0 and anteiso-C15 : 0. No unsaturated fatty acids were detected. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain STH-1-Y1(T) was closely related to the family Chitinophagaceae within the phylum Bacteroidetes. However, the isolate was evenly distant from all members in this family with sequence similarities of 87-89 %. These significantly low sequence similarities strongly suggested that strain STH-1-Y1(T) represents a novel species in a new genus of the family Chitinophagaceae within the phylum Bacteroidetes. Based on phenotypic and phylogenetic characteristics, the name Crenotalea thermophila gen. nov., sp. nov. is proposed. The type strain of the type species is STH-1-Y1(T) ( = JCM 11541(T) = DSM 14807(T)).