A Co-operative Numerical Analysis of Cultures Considered to Belong to the 'rhodochrous' Taxon

Summary: A co-operative taxonomic study has been performed on cultures belonging to the ‘rhodochrous complex'. Phenetic data on 98 cultures (78 rhodochrous cultures, 12 marker cultures with the genus designation Mycobacterium and 8 with the designation Nocardia) studied in four laboratories were collected and analysed by numerical taxonomic methods. The precipitinogenic properties and the presence of different types of mycolic acids were analysed independently to establish correlation with the numerical classification. The chemotaxonomic and serological data correlated well with the numerical analyses. The rhodochrous taxon can be distinguished from the genera Mycobacterium and Nocardia, and from the proposed genus Actinomadura; furthermore, it can be divided into at least three homogeneous subgroups. Further studies however, are needed before the question of the generic location of the rhodochrous taxon can be settled and before the taxonomic status of the rhodochrous subclusters can be resolved.