Deoxyribonucleic Acid Reassociation in the Classification of the Genus Rhodococcus Zopf 1891 (Approved Lists, 1980)

Abstract

We determined the degree of binding between deoxyribonucleic acid (DNA) preparations from representative rhodococci and thymine-labeled DNAs (derived from labeled uracil) from the following six reference strains: Rhodococcus coprophilus (Approved Lists, 1980) strain N744, R. corallinys (Bergey et al. 1923) Goodfellow and Alderson 1979 (Approved Lists, 1980) strain N657, R. equi (Approved Lists, 1980) strain C7, R. rhodochrous (Approved Lists, 1980) strain N54, R. ruber (Approved Lists, 1980) strain N361, and R. rubropertinctus (Hefferan 1904) Goodfellow and Alderson 1979 (Approved Lists, 1980) strain N4. Although the congruence between the DNA reassociation and earlier numerical phenetic data was good, there was evidence that some strains had been misclassified in the numerical phenetic study. In particular, strains labeled R. corallinus (including the type strain of R. corallinus) and R. rubropertinctus belonged to a single DNA homology group. The former name is thus a later, subjective synonym of the latter. The guanine plus cytosine contents of the DNAs of the rhodococci fell within the range of 65 to 73 mo1%.