The use of antibiotics has rapidly increased after the discovery of penicillin made by Alexander Fleming. Since then, thousands of antibiotics from microbial origin have been discovered. The use of antibiotics in the past decades has led to a rapid evolution in microbes because of naturally occurring multi-drug resistant genes to antibiotics, so there is a need for novel antibiotics. Naturally soil is rich in microorganisms capable of antibiotic synthesis. Soil samples from the Siddhapudur region, Coimbatore, Tamil Nadu were screened for antibiotic producing microorganisms by crowded plate technique. Six strains were suspected to produce antibiotics based on the clear zone around the colony. The bacterial species were characterized by its cellular characteristics, colonial morphology and biochemical tests. The isolates tested against Staphylococcus aureus, Proteus vulgaris, Pseudomonas aeruginosa and Escherichia coli for its antibacterial activity. All the isolated colonies were screened for antimicrobial activity. Growth curve of the selected isolate was plotted against time and it was clear that secondary metabolite produced during third day. The results revealed that, though the entire isolates produced clear zone in crowded plate technique five strains fails to show antibacterial activity against tested strains. Isolate I and V produces antibacterial activity. The results suggest that soil isolates from the selected region having antibiotic producing ability and it could be utilized commercially after proper potentiation and standardisation.
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