Bacillus hisashii sp. nov., isolated from the caeca of gnotobiotic mice fed with thermophile-fermented compost

A taxonomic study was performed on 15 bacterial isolates from the caeca of gnotobiotic mice that had been fed with thermophile-fermented compost. The 15 isolates were thermophilic, Gram-stain-positive, facultatively anaerobic, endospore-forming bacteria, and were most closely related to Bacillus thermoamylovorans CNCM I-1378 T . The 16S rRNA gene sequence of strain N-11 T , selected as representative of this new group, showed a similarity of 99.4 % with Bacillus thermoamylovorans CNCM I-1378 T , 94.7 % with Bacillus thermolactis R-6488 T , and 94.4 % with Bacillus kokeshiiformis MO-04 T . The isolates were then classified into two distinct groups based on a (GTG) 5 -fingerprint analysis. Two isolates, N-11 T and N-21, were the representatives of these two groups, respectively.` The N-11 T and N-21 isolates showed 66-71 % DNA-DNA relatedness with one other, but had less than 37 % DNA-DNA relatedness with B. thermoamylovorans LMG 18084 T . The other 13 isolates showed DNA-DNA relatedness values above 74 % with the N-11 T isolate. All 15 isolates grew at 25-60 °C (optimum 50 °C), pH 6-8 (optimum pH 7) and were capable of growing on a medium containing 6 % (w/v) NaCl (optimum 0.5 %). The 15 isolates could be distinguished from B. thermoamylovorans LMG 18084 T because they showed Tween 80 hydrolysis activity and did not produce acid from melibiose. The major fatty acids were anteiso-C 15 : 0 , C 16 : 0 , iso-C 15 : 0 , iso-C 14 : 0 and iso-C 16 : 0 . The major polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol and several unidentified phospholipids. The diagnostic diamino acid in the cell-wall peptidoglycan was meso -diaminopimelic acid. The menaquinone was MK-7. The DNA G+C content was 37.9 mol%. Based on the phenotypic properties, the 15 strains represent a novel species of the genus Bacillus , for which the name Bacillus hisashii sp. nov. is proposed. The type strain is N-11 T ( = NRBC 110226 T  = LMG 28201 T ).