Compostibacillus humi gen. nov., sp nov., a member of the family Bacillaceae, isolated from sludge compost

Two novel Gram-staining-positive, rod-shaped, endospore-forming and moderately thermophilic bacteria, designated strains DX-3(T) and GIESS002, were isolated from sludge composts from Guangdong Province, China. Analysis of 16S rRNA gene sequences revealed that the isolates were closely related to each other with extremely high similarity (99.6%), and were members of the family Bacillaceae. However, these two isolates formed a novel phylogenetic branch within this family. Their closest relatives were the members of the genera Ornithinibacillus, Oceanobacillus and Virgibacillus. Cells of both strains were facultatively anaerobic and catalase- and oxidase-positive. The cell-wall peptidoglycan type was A1 gamma (meso-diaminopimelic acid direct). The predominant isoprenoid quinone was MK-7. The main polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major cellular fatty acid was iso-C-15:0. The DNA G+C content was 43.2-43.7 mol%. The results of a polyphasic taxonomic study indicated that strains DX-3(T) and GIESS002 represent a novel species in a new genus in the family Bacillaceae, order Bacillales, for which the name Compostibacillus humi gen. nov., sp. nov. is proposed. The type strain is DX-3(T) (=KCTC 33104(T)=CGMCC 1.12360(T)).