Optimization of process parameters for production of antimicrobial metabolites by an endophytic fungus Aspergillus sp. CPR5 isolated from calotropis Procera root

Abstract

Objective: To study the antimicrobial activity of crude ethyl acetate extract from endophytic fungus in Calotropis procera root. Methods: Endophytic fungus was screened for production of antimicrobial metabolites. Fermentation was carried out in 500 ml Erlenmeyer flask. Disc diffusion method was used to test antimicrobial activity of crude extract using chloramphenicol sulfate and fluconazole as a positive control. Results: A total of 14 endophytic fungi were isolated (CPR1-CPR14). Among these 14 isolates, CPR5 was found to show maximum antimicrobial activity, in compare to other isolates, against Gram-positive, Gram-negative bacteria and fungi. The antimicrobial activity was tested in opposition to Escherichia coli, Pseudomonas aeroginosa, Bacillus subtilis, Staphylococcus aureus, Ralstonia solanacearum, Xanthomonas oryzae, Penicillium chrysogenum, Candida albicans, Phoma exigua, Sclerotium rolfsii, and Sclerotinia scleratiourum. Minimum inhibitory concentration of crude extract against test microorganisms was determined. Fungus was identified as Aspergillus sp. production parameters (temperature, pH, carbon source, nitrogen source, and sodium chloride concentration) were optimized. Conclusion: Crud extract produced by the isolated endophytic fungus could be an important source of broad-spectrum antimicrobial metabolites. © 2017 The Authors.