Screening of Actinomycete Isolates from Niche Habitats in Manipur for Antibiotic Activity

Problem statement: The exhaustion of the usual terrestrial sources and the rise of resistant pathogens dictate the search for novel actinomycetes and new antibiotics. In this context, niche habitats such as caves, pristine forests, lakes, rivers, and other wetlands, high salt environments, marine ecosystems and endophytic niches are promising targets for survey of bioactive actinomycetes. Approach: Actinomycetes were isolated from several niche habitats in Manipur, India, on selective media such as SCNA and Chitin agar with or without antibiotics. Selected isolates were subjected to antimicrobial activity screening by Kirby-Bauer method. Results: 172 lake sediment (SCNA, LS1 series), 35 lake sediment (CA, LSCH series), 120 river (NRP, NRB and..series), 39 forest (AML series), 35 cave (KC1 series), 101 salt spring (NH, N3S and .. series), 46 Shirui jungle (SJ series) and 66 Shirui hill (SH series) actinomycetes isolates were obtained. Of 99 randomly selected isolates screened, 37 had antimicrobial activities against 1 or more indicator strains: 32 against Gram positive bacteria and 8 against Gram negative bacteria; 10 actinomycete strains were antimycotic and 3 had broad-spectrum antibiotic activities. About 18 potent antibacterial, 1 anti pseudomonas, 1 exclusively antifungal and 3 broad-spectrum antimicrobial actinomycetes were chosen for further studies. Conclusion: Niche habitats in Manipur especially wetlands show great promise for discovery of bioactive actinomycetes.