Numerical taxonomy of cholesterol‐degrading soil bacteria

Abstract

Eighty‐four nocardioform bacteria freshly isolated from soil samples have been compared with 28 marker cultures in a numerical taxonomic study in which 114 unit characters were determined. The strains were recovered in seven major clusters and two minor clusters. Nine strains could not be assigned to any one of the clusters. Six of the major clusters could be identified with named cultures or type strains of Rhodococcus erythropolis, R. rubropertinctus , and R. terrae, R. equi, R. rhodocrous, R. coprophilus and Mycobacterium fortuitum . Three of the local isolates were recovered in a minor cluster related to the M. fortuitum cluster. Three type strains and two marker cultures of the genus Nocardia were grouped in a minor cluster. The remaining major cluster consisted of 16 strains that were identified as rhodococcal strains. However, these 16 strains could not be equated with any of the established Rhodococcus species. It is therefore proposed that these strains be considered a new species within the genus Rhodococcus for which the specific name Rhodococcus australis is proposed. A description of the new species is given.