Production of Antibiotics from Soil-Isolated Actinomycetes and Evaluation of their Antimicrobial Activities

Purpose: To investigate the production of antibiotic from actinomycetes isolated from soil and evaluate its antimicrobial activities. Methods: In a medium formulation study, A-4 and A-4 actinomycete mutant strains (out of the six strains selected from the nine actinomycetes that were screened) were evaluated for maximum antibiotic production using various carbon and nitrogen sources. Zone of inhibition and packed cell volume were the parameters used for the evaluation. Various fermentation conditions such as pH, temperature and dissolved oxygen were also optimized for maximal production of antibiotic from both A-4 and A-4 mutant. Results: Some actinomycetes strains showed promising antimicrobial activity against different strains of bacteria and fungi. Out of the six strains selected, one strain, designated A-4, showed maximum antimicrobial property against Gram positive and Gram negative strains as well as against various fungi. Conclusion: Findings from this investigation reveal that strain A-4 and A-4 mutant strains, in that order, exhibited superior antimicrobial activities to other soil isolates of actinomycetes.