Numerical Classification of Streptomyces and Related Genera

Abstract

Four hundred and seventy-five strains, which included 394 type cultures of Streptomyces and representatives of 14 other actinomycete genera, were studied. Overall similarities of these strains for 139 unit characters were determined by the SSM and SJ coefficients and clustering by the UPGMA algorithm. Test error and overlap between the phena defined were within acceptable limits. Cluster-groups were defined by the SSM coefficient at the 70.1% similarity (S) level and by the SJ coefficient at the 50% S-level. Clusters were distinguished at the 77.5% SSM and 63% SJ S-levels. Groupings obtained with the two coefficients were generally similar, but there were some changes in the definition and membership of cluster-groups and clusters. The phenetic data obtained, together with those from previous diverse studies, indicated that the genera Actinopycnidium, Actinosporangium, Chainia, Elytrosporangium, Kitasatoa and Microellobosporia should be reduced to synonyms of Streptomyces, while Intrasporangium, Nocardioides and Streptoverticillium remained as distinct genera in the family Streptomycetaceae. Nocardiopsis dassonvillei also showed strong phenetic affinity to Streptomyces, despite its chemotaxonomic differences. Actinomadura sensu stricto was phenetically distinguishable from Streptomyces and 'Nocardia' mediterranea was recognized as a taxon distinct from both these genera and from Nocardia sensu stricto. Most of the Streptomyces type cultures fell into one large cluster-group. At the 77.5% SSM S-level, they were recovered in 19 major and 40 minor clusters, with 18 strains recovered as single member clusters. The status of the latter as species was therefore confirmed. Most of the minor clusters, consisting of two to five strains, can also be regarded as species. The major clusters varied in size (from 6 to 71 strains) and in there homogeneity. Therefore, it is suggested that they be regarded as species-groups until further information is available. The results provide a basis for the reduction of the large number of Streptomyces species which have been described. They also demonstrate that the previous use of a limited number of subjectively chosen characters to define species-groups or species has resulted in artificial classifications.

The medically important aerobic actinomycetes: epidemiology and microbiology

“…were described (461). By 1970, the total had increased to 3,100, although many species had been inadequately described or cited in patent literature (592 (638,640) suggested that the significant weighting given to morphologic characters in prior classifications was no longer justified. They suggested that there should be relatively few cluster groups (or species) within the genus and assigned over 300 Streptomyces and Streptoverticillium spp.…”

Agrococcus casei sp. nov., isolated from the surfaces of smear-ripened cheeses

“…The representative isolates and type strains of the three Agrococcus species studied were examined for a range of phenotypic properties using standard procedures: acid production from sugars (Hugh & Leifson, 1953); catalase activity, degradation tests and growth on organic acids as sole carbon sources (Gordon & Mihm, 1957, 1962; aesculin hydrolysis (Williams et al, 1983); allantoin and urea hydrolysis (Cowan, 1974); nitrate reduction and hydrogen sulphide production (Gordon, 1968); degradation of Tweens (Sierra, 1957); and the breakdown of glycerol tributyrate using tributyrin agar (Sigma). All tests were incubated at 30 uC for 14 days.…”

Actinobacteria Isolation from Metal Contaminated Soils for Assessment of their Metal Resistance and Plant Growth Promoting (PGP) Characteristics

“…Species under Streptomyces were first identified for their antibiotic production, which lead to overspeciation in the taxon, from an initial number of 40 species to more than 3000. Only after the launching of the International Streptomyces Project (ISP) which introduced keys identification criteria based on morphological aspect and numerical taxonomy by Williams et al, (1983) was this overspeciation limited and redescription of more than 450 species was done (Annaliesa and Wellington, 2001). Attention to nitrogen fixation among actinobacteria was focused only on genus Frankia, which are able to make symbiotic relationships with a range of actinorhizal plants (Benson and Silvester, 1993).…”