Quantitative intra- and intergeneric taxonomic relationships among Micrococcaceae strains reveal contradictions in the historical assignments of the strains and indicate the need for species reclassification.

This article reports the results of quantitative intra- and intergeneric taxonomic relationships among Micrococcaceae strains and a novel endophytic bacterium (SG) isolated from a suspension culture of Arabidopsis thaliana (L.) Heynh in our laboratory. The known strain Rothia sp. ND6WE1A was used as a reference one for SG. Whole-genome sequencing and phylogenetic analysis were based on the 16S rRNA test. Quantitative analysis for the nucleotide identity (ANI) and calculation of evolutionary distances were based on the identified amino acids (AAI) test indicating the generic assignment of the reference strain within and between the identified monophyletic groups of Micrococcaceae. The amino acid data structure of Rothia sp. ND6WE1A was compared against the UniProt database (250 million records) of close lineage of Micrococcaceae, including other Rothia spp. These data presented unique and evolutionary amino acid alignments, eventually expected in the new SG isolate as well. The metagenomic entries of the respective genome and proteome, characterized at the genus and species levels, could be considered for evolutionary taxonomic reclassification of the isolated and the reference strain (SG + Rothia sp. ND6WE1A). Therefore, our results warrant further investigations on the isolated SG strain.