R.N. JADHAV
Abstract
Actinomycetes are ubiquitous group of bacteria that occur in multiplicity of natural and man made environments. They are predominantly Gram positive bacteria with high G+C % (57-79 %). Several species of actinomycetes produce antibiotics of agricultural and industrial importance. Biocontrol of plant pathogen is an attractive alternative to chemical pesticides which causes environmental pollution and development of resistant strain. Majority of antibiotics so far isolated were produced from Streptomycetes, which are common inhabitants of the soil. There are 23,000 known secondary metabolite, 42% of which are produced by actinomycetes, 42% by fungi and 16% by other bacteria. In the present study screening of actinomycetes from rhizosphere of sugarcane was done by using specific media. Plates were incubated at 28oC for 4-14 days. Ten isolates of actinomycetes were isolated. They were further purified and identified by using several biochemical tests. The antimicrobial activity of isolates of actinomycetes was studied by using agar diffusion (well) method against Bacillus megaterium NCIM2326; Candida albicans NCIM3103; Escherichia coli NCIM2064; Fusarium oxysporium (soil isolate) and Xanthomonas compestris NCIM2956. It was observed that isolates of actinomycetes ISS06 showed maximum antimicrobial activity against all test organisms. The morphology along with cultural and biochemical tests confirmed that these isolates belonged to genus Streptomyces.