Tepidimicrobium xylanilyticum sp. nov., an anaerobic xylanolytic bacterium, and emended description of the genus Tepidimicrobium.

A novel, xylanolytic, anaerobic, moderately thermophilic bacterium, strain PML14(T), was isolated from the sludge of a thermophilic anaerobic digester treating municipal solid waste and sewage in Beijing, China. The strain was a Gram-positive, spore-forming and motile rod. Growth of the novel strain was observed at 25-67 degrees C (optimum 60 degrees C) and pH 5.8-9.3 (optimum pH 8.5). Strain PML14(T) grew on a number of carbohydrates, including xylan, xylose, glucose and cellobiose, and a variety of proteinaceous compounds, including peptone, tryptone, Casamino acids, yeast extract, beef extract, casein hydrolysate, l-cysteine, l-serine, l-lysine, l-glycine, l-threonine, l-methionine and pyruvate. The fermentation products from glucose included acetate, ethanol, butyrate, hydrogen and carbon dioxide. Propionate was produced from xylan in addition to other compounds. Fe(III), 9,10-anthraquinone 2,6-disulfonate and thiosulfate were reduced with peptone as the electron donor. NH(3) was produced. Indole was not produced. Gelatin was not hydrolysed. The DNA G+C content of strain PML14(T) was 36.2+/-0.8 mol% (T(m)). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain PML14(T) was related to the members of cluster XII of the clostridia, most closely to Tepidimicrobium ferriphilum SB91(T) with 93.8 % 16S rRNA gene sequence similarity. On the basis of polyphasic evidence from this study, it is suggested that strain PML14(T) (=CGMCC 1.5080(T)=JCM 15035(T)) represents a novel species of the genus Tepidimicrobium, for which the name Tepidimicrobium xylanilyticum sp. nov., is proposed. An emended description of the genus Tepidimicrobium is also provided.