DNA Base Composition and Taxonomy of Some Micrococci

SUMMARY The present report gives the results of studies on the % guanine+cytosine (GC) content of the DNA of 29 strains designated as Micrococcus, by using the methods of Marmur & Doty (1962) and Frédéricq, Oth&Fontaine (1961). In 17 strains agreement was found between their taxonomic position and their % GC content. Five micrococci formed a very tight cluster around a mean of 50% GC. It is recommended to classify them in the genus Planococcus Migula. From the DNA base compositions these cocci form a group hitherto not described, intermediate between the genera Staphylococcus and Micrococcus. Micrococcus cryophilus McLean, Sulzbacher&Mudd, and Micrococcus cerolyticus Friedman&Kern differ in their % GC values from those of the genus Micrococcus and should be discarded from the genus. It is confirmed that % GC content in the DNA in the genus Micrococcus lies within the range of 65–75%.