Stimulatory effect of copper on antibiotic production and morphological differentiation in Streptomyces tanashiensis.

The Gram-positive bacterial genus Streptomyces has two characteristic features; one is its productivity of a wide variety of secondary metabolites such as antibiotics or other biologically active compounds, and the other is its ability to perform cellular-differentiation from substrate hyphae into aerial mycelium and spores1'2). These phenotypic features of Streptomyces are knownto be induced by extracellular signal molecules produced by the organism itself. For example, A-factor, a ybutyrolactone derivative, is produced by Streptomyces griseus and induces both its streptomycin production and initiation of development into aerial mycelium at a concentration as low as 10~9m3~5). Involvement of a series of A-factor analogues6) as well as some polypeptidic signals7) have been observed with secondary metabolism and morphogenesis in various Streptomyces spp. During the course of our systematic screening targeting such extracellular signalling substances in