Defluviitalea raffinosedens sp. nov., a thermophilic, anaerobic, saccharolytic bacterium isolated from an anaerobic batch digester treating animal manure and rice straw

Abstract

A thermophilic, anaerobic, fermentative bacterium, strain A6T, was obtained from an anaerobic batch digester treating animal manure and rice straw. Cells were Gram-stain-positive, slightly curved rods with a size of 0.6–1×2.5–8.2 μm, nonmotile and produced terminal spores. The temperature, pH and NaCl concentration ranges for growth were 40–60 °C, 6.5–8.0 and 0–15.0 g l–1, with optimum growth noted at 50–55 °C, pH 7.5 and in the absence of NaCl, respectively. Yeast extract was required for growth. D-Glucose, maltose, D-xylose, D-galactose, D-fructose, D-ribose, lactose, raffinose, sucrose, D-arabinose, cellobiose, D-mannose and yeast extract were used as carbon and energy sources. The fermentation products from glucose were ethanol, lactate, acetate, propionate, butyrate, valerate, iso-butyrate, iso-valerate, H2 and CO2. The G+C content of the genomic DNA was 36.6 mol%. The predominant fatty acids were C16: 0, iso-C17: 1, C14: 0, C16: 1ω7c, C16: 0 N-alcohol and C13: 0 3- OH. Respiratory quinones were not detected. The polar lipid profile comprised phosphoglycolipids, phospholipids, glycolipids, a diphosphatidylglycerol, a phosphatidylglycerol and an unidentified lipid. Phylogenetic analyses of the 16S rRNA gene sequence indicated that the strain was closely related to Defluviitalea saccharophila DSM 22681T with a similarity of 96.0%. Based on the morphological, physiological and taxonomic characterization, strain A6T is considered to represent a novel species of the genus Defluviitalea, for which the name Defluviitalea raffinosedens sp. nov. is proposed. The type strain is A6T (=DSM 28090T=ACCC 19951T).