Screening and Isolation of the Soil Bacteria for Ability to Produce Antibiotics

Antibiotic is one of the most important commercially exploited secondary metabolites produced by bacteria 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 bacitracin etc. are always found inhibiting the growth of the other organisms. In the present research study, soil bacteria with the antibiotic activity was screened and isolated. The media used in this research was nutrient agar medium. 1g of the soil samples were dissolved in 10ml of sterile water to make soil suspensions. Portion of the suspensions were inoculated on the nutrient agar by streaking and were incubated at 37°C for 24 hours. After which colonies with a clear zone of inhibition were observed. The bacteria isolated were; Bacillus lentus, Micrococcus roseus, Bacillus alvei, Enterobcteraerogene and Bacillus pumillus. The inhibitory activities of the isolated microorganisms were checked against some of the important opportunistic microflora like Staphylococcus aureus and Pseudomonas species.