ANTIBIOTIC PRODUCTION BY MICROBES ISOLATED FROM SOIL

Antibiotic is one of the most important commercially exploited secondary metabolites produced by bacteria, fungi and Streptomyces and employed in a wide range. Most of the antibiotics used today are from the microbes. Bacteria are easy to isolate, culture, maintain and to improve their strain. Bacillus species being the predominant soil bacteria because of their resistant endospore formation and production of vital antibiotic like polymyxin, bacitracin etc. are always found inhibiting the growth of the other organisms. In the present research study, screening of bacteria, fungi and Streptomyces with potential antibiotic activity was carried out. Among the microbes isolated and identified, Bacillus subtilis, Penicillium chrysogenum and Streptomyces spwere selected on the basis of their anti-bacterial activity. The inhibitory activities of the isolated microorganisms were checked against Staphylococcus aureus (ATCC 29213), Pseudomonas aeruginosa (ATCC 27853), Escherichia coli (ATCC 25922) and Klebsiella pneumonia (ATCC 4352). It was observed that Penicillium chrysogenum metabolites showed maximum antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli and Klebsiella pneumonia with a zone of inhibition of 17mm, 11mm, 19.8mm and 8.2mm respectively. Bacillus subtilis metabolites showed activity against Staphylococcus aureus and Pseudomonas aeruginosa measured as zone of inhibition of 13.4mm and 13.8mm respectively whereas Streptomyces sp showed minimum activity against all the four tested organisms.