ISOLATION AND CHARACTERIZATION OF BIOACTIVE ACTINOMYCETES FROM SOIL IN AND AROUND NAGPUR

ABSTRACT: Fifteen soil samples were collected from different locations near Nagpur i.e. from Nagpur, Bhandara and Chandrapur. Air drying and pre-treatment of soil samples with CaCo₃ (1%) were found to be most effective for isolation of actinomycetes. Five different selective media were used for the isolation of actinomycetes and the best growth was observed in yeast malt extract agar medium with 1 mg/ml cycloheximide as antifungal agent and by using double layer agar technique for isolation. Significant differences were found between the counts of actinomycetes on different media. Total 78 actinomycetes species were isolated. More number of actinomycetes were isolated from Nagpur region (32 x 10 cfu/g) as compared to Bhandara (28 x 10 cfu/g) and Chandrapur (18 x 10 cfu/g) regions. Out of 78 isolates 23 isolates showed positive results in primary screening. Maximum isolates showed activity against B. subtilis, B. cereus, S. aureus and E. coli. Few isolates showed activity against P. vulgaris, P. aeruginosa, C. albicans and A. niger. Noactivity was seen against Penicillium sp. From 23 isolates 20 isolates showed good results in secondary screening. Finally one isolate was selected for further identification based on its broad spectrum activity and larger zone of inhibition compared to others. Phenotypic identification and biochemical and physiological characteristics of the isolated species were performed at MTCC Chandigarh and was identified as Streptomyces violaceorubidus and the strain was designated as RC 1796. These investigations clearly indicate that Nagpur and nearby area is a potent source for the isolation of bioactive actinomycetes useful for production of antimicrobial substances.