STREPTOMYCES-THERMOCARBOXYDOVORANS SP. NOV. AND STREPTOMYCES-THERMOCARBOXYDUS SP. NOV., 2 MODERATELY THERMOPHILIC CARBOXYDOTROPHIC SPECIES FROM SOIL

Four moderately thermophilic, carboxydotrophic streptomycetes were the subject of a comparative taxonomic investigation designed to establis h their taxonomic relationships. Almost complete sequences of the 16S rRNA genes of the test strains were determined following the isolation and direct sequencing of the amplified genes, The resultant nucleotid e sequences were aligned with the sequences of previously studied stre ptomycetes, and phylogenetic trees generated by using the neighbour-jo ining, Fitch-Margoliash, maximum-likelihood and maximum-parsimony meth ods. It was evident from the phylogenetic analyses that strains AT50, AT51 and AT52 were most closely related to Streptomyces thermodiastati cus DSM 40573(T) and strain AT37 to Streptomyces glaucescens DSM 40716 and Streptomyces pseudogriseolus NRRL 3985. Random DNA amplification profiles clearly distinguished strains AT50, AT51 and AT52 from Strept omyces thermodiastaticus and from strain AT37. The molecular systemati c evidence, together with phenotypic data derived from this and previo us studies, indicate that the test strains merit species status within the genus Streptomyces. The name Streptomyces thermocarboxydovorans s p. nov. is proposed for strains AT50, AT51 and AT52 (type strain) and Streptomyces thermocarboxydus sp. nov. for strain AT37.