Studies on the production of actinomycin-D by Streptomyces griseoruber - a novel source

Aims: To isolate and characterize bioactive metabolites produced by a micro-organism isolated from a soil sample associated with the roots of a medicinal plant, Azadirachta indica. Methods and Results: Morphological, cultural, physiological and 16S rRNA homology studies revealed that the organism showed 99% similarity with Streptomyces griseoruber NBRC 12873. One bioactive metabolite (Py2) isolated from the fermented broth was characterized as actinomycin-D (act-D). It showed high activity against various Gram-positive and Gram-negative bacterial cultures, Mycobacterium tuberculosis H37Rv and human neoplastic cells in vitro using standard protocols. Conclusions: The isolated strain S. griseoruber produced act-D predominantly (210 mg l<SU-1</SU, c. 88% of the crude) under nonoptimized growth conditions. Significance and Impact of the Study: Streptomyces griseoruber may be exploited as a potential source for the commercial production of act-D, as this strain is not reported to produce act-D. Further investigations on the strain for commercial application will be of immense pharmaceutical importance.