Novibacillus thermophilus gen. nov., sp nov., a Gram-staining-negative and moderately thermophilic member of the family Thermoactinomycetaceae

Two Gram-staining-negative, facultatively anaerobic bacterial strains, SG-1(T) and SG-2, were isolated from a saline soil sample and a compost sample, respectively. The cells were non-motile rods that occurred singly or in chains, and endospores were not observed under tested growth conditions. Optimum growth occurred at 50 degrees C, pH 7.5-8.0 and with 5-7% (w/v) NaCI. The DNA G+C content was 49.5-50.5 mol%. The strains contained MK-7 as the predominant menaquinone and iso-C-15:0 and anteiso-C-15:0 as the major fatty acids. The polar lipids consisted mainly of diphosphatidylglycerol and phosphatidylglycerol. The cell-wall peptidoglycan type was A1 gamma (meso-DAP direct). Phylogenetic analyses revealed that the new isolates belonged to the family Thermoactinomycetaceae, exhibiting low 16S rRNA gene sequence similarity (90.8-91.3%) to the nearest type strain, Mechercharimyces asporophorigenens YM11-542(T), and formed a well-supported lineage that was clearly distinguished from all currently described genera in this family. Based on our polyphasic taxonomic characterization, we propose that strains SG-1(T) and SG-2 represent a novel genus and species within the family Thermoactinomycetaceae, for which we propose the name Novibacillus thermophilus gen. nov., sp. nov. The type strain of Novibacillus thermophilus is SG-1(T) (=KCTC 33118(T)=CGMCC 1.12771(T)).