Dictyobacter aurantiacus gen. nov., sp. nov., a member of the family Ktedonobacteraceae, isolated from soil, and emended description of the genus thermosporothrix

A mesophilic, Gram-stain-positive, spore-forming bacterium that formed branched mycelia was isolated from paddy soil in Gunung Salak (Mount Salak), West Java, Indonesia. This strain, designated S-27^T, grew at temperatures between 20 and 37 °C; the optimum growth temperature was 25 to 30 °C, and no growth was observed at 15 or 45 °C. The pH range for growth was pH 3.5 to 8.6; the optimum pH was 6.0, and no growth was observed at pH 3.0 or 9.2. Strain S-27^T was able to hydrolyse polysaccharides such as starch, cellulose and xylan. The G+C content of the DNA of strain S-27^T was 55.7 mol%. The major fatty acids were iso-C_{17: 0} and C_{16: 1} 2-OH, and the major menaquinone was MK-9 (H₂₎. The cell wall of strain S-27^T contained Dglutamic acid, glycine, L-alanine, D-alanine, L-ornithine and β-alanine in a molar ratio of 1.0: 1.6: 1.4: 0.6: 0.9: 1.1. The polar lipids consisted of phosphatidylglycerol, phosphatidylinositol and two glycolipids. The major cell-wall sugar was arabinose. Detailed phylogenetic analysis based on 16S rRNA gene sequences indicated that strain S-27^T belongs to the order Ktedonobacterales and is most closely related to Ktedonobacter racemifer SOSP1-21T (89.6% sequence identity). On the basis of its chemotaxonomic and phenotypic features and phylogenetic position, we concluded that strain S-27^T represents a novel genus and species, for which we propose the name Dictyobacter aurantiacus gen. nov., sp. nov. The type strain of Dictyobacter aurantiacus is strain S-27^T (=NBRC 109595^T=InaCC B312^T). Emendation of the description of the genus Thermosporothrix is also provided.