Numerical classification of thermophilic streptomycetes

SUMMARY: Fifty thermophilic streptomycetes from diverse habitats were compared through 135 unit characters with 201 representative mesophilic streptomycetes from an earlier numerical phenetic study. Data were examined using the simple matching (S SM), Jaccard (S J) and pattern (D P) coefficients, and clustering was achieved using the unweighted pair group method with arithmetic averages (UPGMA) technique. In all three analyses, the thermophilic streptomycetes formed an aggregate taxon composed of three major (seven to nineteen strains), five minor (two to three strains) and two single-member clusters. Cluster composition was not affected by the statistics used. The numerical phenetic data showed that thermophilic streptomycetes form several distinct centres of variation, four of which correspond to previously described species; a further taxon was also considered to merit species status. It is proposed that Streptomyces thermolineatus sp. nov. be recognized and the name Streptomyces macrosporus Krassilnikov et al. 1968 be revived. Emended descriptions are given for Streptomyces megasporus (Krassilnikov et al., 1968) Agre 1983, Streptomyces thermoviolaceus Henssen 1957 and Streptomyces thermovulgaris Henssen 1957.