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

Abstract

A Gram-negative, rod-shaped, spore-forming and moderately thermophilic bacterium, strain KWC4T, was isolated from a composting reactor. Cells of strain KWC4T were 2.0–5.0 μm long and 0.5–0.7 μm in diameter. Strain KWC4T grew aerobically at 32–61 °C, with optimal growth occurring at 50 °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 KWC4T was moderately halotolerant and was able to grow at NaCl concentrations up to 4.4 % (w/v). The DNA G+C content of strain KWC4T 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 KWC4T belonged to the genus Thermobacillus and was related to Thermobacillus xylanilyticus. However, strain KWC4T had a 38 bp insertion sequence located near the 3′ end of its 16S rRNA gene that was not present in T. xylanilyticus. The 16S rRNA gene sequence similarity value between strain KWC4T and T. xylanilyticus was 95.7 %. The DNA–DNA hybridization value between strain KWC4T and T. xylanilyticus strain XET was 66 %. On the basis of phenotypic and genotypic evidence, strain KWC4T (=DSM 18247T=JCM 13945T) is the type strain of a novel species, for which the name Thermobacillus composti sp. nov. is proposed.