Isolation and Identification of Streptomyces from Soils

Environmental bacteria particularly the species of the genus Streptomyces that belong to the actinomycetes group of bacteria have been a major source of clinically used antibiotics. From the soils collected from Rajshahi University campus 30 actinomycetes were isolated and 16 of them were found to have moderate to high antibacterial activity against a group of test bacteria. One of the highly active isolates, MARS-17 was identified as Streptomyces parvulus based on its morphological, cultural, physiological characteristics and 16S rDNA sequence homology data. An active pure compound MAR-1 was isolated from the fermentation broth of MARS-17. The chemical structure of the compound was established as Actinomycin D on the basis of its 1H-NMR, 13C-NMR, DEPT 135° and Mass spectral data. The compound showed significant antimicrobial activity against a group of test bacteria, however, no antifungal activity was observed. The MIC of the compound was in the range of 2-8 ¿g/ml against a wide range of test bacteria. The detailed methods of isolation, characterization and study of the biological activities of ethyl acetate extracts of Streptomyces have been covered in this book.