Abstract

In the present study, phylogenetic and genome-based comparison was carried out to clarify the taxonomic positions of alkaliphilic Bacillus species, Bacillus plakortidis, Bacillus lehensis, Bacillus oshimensis, Bacillus rhizosphaerae and Bacillus clausii. Phylogenetic trees based on 16S rRNA gene sequences and concatenated protein marker genes were constructed. Average nucleotide identity (ANI) values were calculated to compare genetic relatedness. In phylogenetic trees, B. plakortidis DSM 19153(T), B. lehensis DSM 19099(T), and B. oshimensis DSM 18940(T); B. rhizosphaerae DSM 21911(T) and B. clausii DSM 8716(T) clade together. The average nucleotide identity (ANI) values between B. oshimensis DSM 18940(T), B. plakortidis DSM 19153(T) and B. lehensis DSM 19099(T) ranged from 98.7-98.8%, while the ANI values between B. rhizosphaerae DSM 21911(T) and B. clausii DSM 8716(T) were 95.2-95.5%. The ANI values were higher than the recognized threshold value for bacterial species delineation. Based on phylogenetic and genome comparison we propose reclassification of B. plakortidis and B. lehensis as a later heterotypic synonym of B. oshimensis; B. rhizosphaerae as a later heterotypic synonym of B. clausii.