Isolation and screening of Streptomyces in soil of protected forest areas from the states of Assam and Tripura, India, for antimicribial metabolites

Objective. - To study the antimicrobial of Antinomycets, isolated from Northeast India. Material and methods. - A total of 110 actinomycetes strains were isolated from the soil samples collected from the protected forest soil from two States in Northeast India These were then characterized by conventional methods and assessed for their antagonistic activity preliminary against test microorganisms. Results. - Among the 110 isolates, 65 (59.09%) strains showed antibacterial activity, 47 (42.72%) strains showed antifungal activity and 33 (30%) strains exhibited a broad-spectrum activity against both test bacteria and fungi. The production of nonpolyenic antifungal substances by promising isolates was investigated using several criteria: antibacterial activity, ergosterol inhibition, and UV-vis spectra of active extracts. Conclusion. - These results indicate that the protected areas of Northeast India's soil microorganisms could be an interesting source of antibacterial and antifungal bioactive substances. (C) 2007 Elsevier Masson SAS. All rights reserved.