Isolation and Characterization of Antibiotic Production from Soil Isolates by Fermentation

In screening of new antibiotics, several actinomycetes were isolated from soil samples. Crowded plate technique was used for the isolation of actinomycetes. The morphological and cultural characterization of A-4 strain was performed. In medium formulation study for A-4 and A-4 mutant, various carbon and nitrogen sources were tested for maximum antibiotic production using zone of inhibition and packed cell volume (%) as parameters. Various fermentation conditions like pH, temperature and DO₂ were also optimized for the maximal production of antibiotic from both A-4 and A-4 mutant. All medium formulation as well as bioprocess parameters for A-4 and A-4 mutant strains was compared. Some actinomycetes strains, showed promising antimicrobial scores against different strains of bacteria and fungi. From the six strains selected, one strain designated as A-4 showed maximum antimicrobial property against gram positive and gram negative strains as well as various fungi. Morphological and cultural studies showed that A-4 is belongs to actinomycete genus.. The strain A-4 and A-4 mutant was found to be having better antimicrobial activity in comparison with other soil isolates of actinomycetes.