Cellulosibacter alkalithermophilus gen. nov., sp. nov., an anaerobic alkalithermophilic, cellulolytic-xylanolytic bacterium isolated from soil of a coconut garden.

An obligately anaerobic, cellulolytic-xylanolytic bacterium, designated strain A6(T), was isolated from soil of a coconut garden in the Bangkuntien district of Bangkok, Thailand. The strain was Gram-stain positive, catalase-negative, endospore-forming, motile and rod-shaped with a cell size of 0.2-0.3×2.0-3.0 µm. Optimal growth of strain A6(T) occurred at pH(55 °C) 9.5, 55 °C. Strain A6(T) fermented various carbohydrates, and the end products from the fermentation of cellobiose were acetate, ethanol, propionate and a small amount of butyrate. The major cellular fatty acids were iso-C(14:0) 3-OH, iso-C(15:0), iso-C(16:0) and C(16:0). The cell-wall peptidoglycan contained meso-diaminopimelic acid. No respiratory quinones were detected. The DNA G+C content was 30.0 mol%. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the strain represented a new phyletic sublineage within the family Clostridiaceae, with <93.0% 16S rRNA gene sequence similarity to recognized species of this family. On the basis of phenotypic, genotypic and physiological evidence, strain A6(T) represents a novel species of a new genus, for which the name Cellulosibacter alkalithermophilus gen. nov., sp. nov. is proposed. The type strain of the type species is A6(T) ( = TISTR 1915(T) = KCTC 5874(T)).