Genome-based reclassification of Bacillus cibi as a later heterotypic synonym of Bacillus indicus and emended description of Bacillus indicus.

Abstract

While characterizing a related strain, it was noted that there was little difference between the 16S rRNA gene sequences of Bacillus indicus LMG 22858(T) and Bacillus cibi DSM 16189(T). Phenotypic characterization revealed differences only in the utilization of mannose and galactose and slight variation in pigmentation. Whole genome shotgun sequencing and comparative genomics were used to calculate established phylogenomic metrics and explain phenotypic differences. The full, genome-derived 16S rRNA gene sequences were 99.74% similar. The average nucleotide identity (ANI) of the two strains was 98.0%, the average amino acid identity (AAI) was 98.3%, and the estimated DNA-DNA hybridization determined by the genome-genome distance calculator was 80.3%. These values are higher than the species thresholds for these metrics, which are 95%, 95% and 70%, respectively, suggesting that these two strains should be classified as members of the same species. We propose reclassification of Bacillus cibi as a later heterotypic synonym of Bacillus indicus and an emended description of Bacillus indicus.