Micrococcus aloeverae,Micrococcus endophyticus, Micrococcus luteus and Micrococcus yunnanensis are phenotypically and genotypically closely related, and together comprise the M. luteus group. In this study, the taxonomic relationships among Micrococcus aloeverae, M. luteus and M. yunnanensis were re-evaluated by using polyphasic approaches. The similarity values of the concatenated housekeeping gene (gyrB, recA and rpoB) sequences shared by the type strains of M. aloeverae, M. luteus and M. yunnanensis ranged from 98.3 to 99.4 %. The average nucleotide identity, average amino acid identity and digital DNA‒DNA hybridization values among these three taxa were greater (97.1‒98.1 %, 96.8‒98.1 % and 75.0‒83.5 %, respectively) than the thresholds for bacterial species delineation, indicating that they belong to the same species, whereas those for M. endophyticus were clearly lower than the thresholds. In addition, phenotypic and chemotaxonomic characterization results also support the synonymy of these three taxa. Therefore, we propose that M. aloeverae and M. yunnanensis should be reclassified as later heterotypic synonyms of M. luteus.
Keywords: Micrococcus aloeverae; Micrococcus luteus; Micrococcus yunnanensis; polyphasic analysis; reclassification; synonym.