Reclassification of Brevibacterium frigoritolerans as Peribacillus frigoritolerans comb. nov. based on phylogenomics and multiple molecular synapomorphies

The taxonomic assignment of Brevibacterium frigoritolerans together with the in-house environmental isolate EB93 was reassessed in this study using phylogenetic and phylogenomic approaches, and the detection of multiple molecular synapomorphies. Results from the reconstructed phylogenetic trees based on the 16S rRNA gene sequences, the concatenated protein sequences of GyrA-GyrB-RpoB-RpoC, and the whole-genome sequences revealed the consistent exclusion of B. frigoritolerans and the environmental isolate EB93 from the cluster formed by the type strains of the genus Brevibacterium. In addition, B. frigoritolerans and the environmental isolate EB93 were both observed to form a clade together with the type strains of the genus Peribacillus. The results from the analysis of the digital DNA-DNA hybridization, average nucleotide identity, average amino acid identity and the difference in the G+C content also corroborated with the phylogenetic inference, and that B. frigoritolerans and the environmental isolate EB93 were of the same species. Furthermore, the presence of the molecular synapomorphies in the protein sequences noted in the description of the genus Peribacillus were also observed in B. frigoritolerans, further strengthening its taxonomic affiliation in the genus. Based on the evidence from the multiple lines of analyses, we propose the reclassification of Brevibacterium frigoritolerans as a member of the genus Peribacillus and assume the name Peribacillus frigoritolerans comb. nov. (type strain DSM 8801 T=ATCC 25097T=CCUG 43489T=CIP 67.20T=JCM 11681T).