Brevibacillus composti sp. nov., isolated from hyperthermophilic compost

Two aerobic, Gram- stain- positive, rod- shaped, endospore- forming, thermophilic bacterial strains, designated FJAT- 54423T and FJAT- 54424, were isolated from hyperthermophilic compost sampled in Shanxi Province, PR China. Growth was observed at 30-60 degrees C (optimum, 50 degrees C) and pH 6.0-9.0 (optimum, pH 7.0), with up to 2.0 % (w/v) NaCl (optimum, 0 % NaCl). The 16S rRNA gene sequence similarity between FJAT- 54423T and FJAT- 54424 was 99.9%, and the maximum similarity to a valid taxon was observed with Brevibacillus borstelensis (98.3%). Further, in phylogenetic and phylogenomic trees, strains FJAT- 54423T and FJAT- 54424 branched with members of the genus Brevibacillus. The menaquinone was MK- 7, and the major fatty acids were iso-C15: 0 and anteiso- C15:0. The main polar lipids included phosphatidylmethylethanolamine, phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol. The cell- wall peptidoglycan was found to contain meso-diaminopimelic acid. The DNA G+C content of strains FJAT- 54423T and FJAT- 54424 were 54.3 and 54.4 mol%, respectively. The average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values of strain FJAT- 54423T and its most closely related reference strain B. borstelensis DSM 6347T were 77.7 and 21.5 %, respectively, which were lower than the recommended species delineation thresholds of ANI (95%) and dDDH (70%). Based on the observed physiological properties, chemotaxonomic characteristics and ANI and dDDH values, FJAT- 54423T and FJAT- 54424 belong to a novel species of the genus Brevibacillus, for which the name Brevibacillus composti sp. nov. is proposed. The type strain is FJAT- 54423T (=GDMCC 1.2054T=KCTC 43273T).

Automated summary

Two thermophilic bacterial strains, designated FJAT-54423T and FJAT-54424, were isolated from hyperthermophilic compost in Shanxi Province, PR China. They belong to a novel species of the genus Brevibacillus, named Brevibacillus composti, based on physiological properties, chemotaxonomic characteristics, and genetic analysis. These strains show high sequence similarity and phylogenetic relationship with Brevibacillus borstelensis.