Taxonomic Dissection of the Genus Micrococcus: Kocuria gen. nov., Nesterenkonia gen. nov., Kytococcus gen. nov., Dermacoccus gen. nov., and Micrococcus Cohn 1872 gen. emend.

This study demonstrates that the genus Micrococcus is phylogenetically heterogeneous and should be divided into five genera. Researchers analyzed 16S rDNA sequences and chemotaxonomic properties of eight Micrococcus species and related organisms. The phylogenetic analysis revealed that Micrococcus species do not cluster together but form four separate lineages within the Arthrobacter line of descent. Only Micrococcus luteus and Micrococcus lylae remain in the genus Micrococcus because they group phylogenetically together and with Arthrobacter globiformis. Four new genera were established: Kocuria (containing M. roseus, M. varians, and M. kristinae), Nesterenkonia (containing M. halobius), Kytococcus (containing M. nishinomiyaensis), and Dermacoccus (containing M. sedentarius). Chemotaxonomic analyses of menaquinone composition, fatty acids, polar lipids, and peptidoglycan supported the phylogenetic divisions. This taxonomic reorganization provides a more accurate classification reflecting the true evolutionary relationships of these bacteria.

Key findings

• The genus Micrococcus is phylogenetically heterogeneous and should be divided into five separate genera based on 16S rDNA sequence analysis.
• Micrococcus luteus and M. lylae are the only species that remain in the genus Micrococcus; all other previously classified Micrococcus species are reclassified into four new genera.
• Chemotaxonomic properties including menaquinone composition, fatty acid profiles, and peptidoglycan types corroborate the phylogenetic divisions revealed by molecular analysis.
• Four new genera were established with specific species combinations: Kocuria, Nesterenkonia, Kytococcus, and Dermacoccus, each supported by distinct molecular and chemical characteristics.