Thermobacillus composti sp nov., a moderately thermophilic bacterium isolated from a composting reactor

A Gram-negative, rod-shaped, spore-forming and moderately thermophilic bacterium, strain KWC4(T), was isolated from a composting reactor. Cells of strain KWC4(T) were 2.0-5.0 mu m long and 0.5-0.7 mu m in diameter. Strain KWC4(T) grew aerobically at 32-61 degrees C, with optimal growth occurring at 50 degrees C. It grew at pH 5.6-10.1, with optimal growth at around pH 9.0. The optimum NaCl concentration for growth was almost 0 % (w/v), but strain KWC4(T) was moderately halotolerant and was able to grow at NaCl concentrations up to 4.4 % (w/v). The DNA G + C content of strain KWC4(T) was 60.0 mol%. The major fatty acids were iso-16:0(39.0%) and anteiso-15:0 (33.3 %). Based on 16S rRNA gene sequence similarity data, strain KWC4(T) belonged to the genus Thermobacillus and was related to Thermobacillus xylanilyticus. However, strain KWC4(T) had a 38 bp insertion sequence located near the 3 ' end of its 16S rRNA gene that was not present in T xylanilyticus. The 1 6S rRNA gene sequence similarity value between strain KWC4(T) and T. xylanilyticus was 95.7 %. The DNA-DNA hybridization value between strain KWC4(T) and T. xylanilyticus strain XET was 66 %. On the basis of phenotypic and genotypic evidence, strain KWC4(T) (=DSM 18247(T) =JCM 13945(T)) is the type strain of a novel species, for which the name Thermobacillus composti sp. nov. is proposed.