Optimization of Fermentation and Production of Antimicrobial Agents as Secondary Metabolites from an Indigenous Aspergillus niger
Optimization of Fermentation and Production of Antimicrobial Agents as Secondary Metabolites from an Indigenous Aspergillus niger
Fizza Anwar1, Muddassar Zafar1*, Zahid Anwar1, Raja Tahir Mehmood2
ABSTRACT
Fungal strains are being exploited extensively for their potential in synthesizing antimicrobial agents. In the present research work, four fungal strains Rhizopus stonolifer, Aspergillus niger, Aspergillus fumigatus and Aspergillus terreus were tested for the production of antimicrobial agents. The produced antimicrobial metabolites included Aflatrem, Monacolin K, Fusarubin and Tautomycetin. Different fermentation parameters were optimized to produce antimicrobial agents using Response Surface Methodology (RSM) and best results were obtained at 45°C temperature, 5.5 pH, 5 mL inoculum concentration, 1.5 mL banana peel as substrate and 20 days incubation time. The antimicrobial activity of secondary metabolites was tested against Streptococcus aglactaie, Streptococcus pyogene, Escherichia coli and Proteus mirabilis. The fungus Aspergillus niger was found best among all tested strains as it produced maximum amount of antimicrobial agent Tautomycetin. The antimicrobial activities were determined through disk diffusion assays and Tautomycetin was observed as best antimicrobial agent having inhibitory effect on serine/threonine phosphatases leading to hindrance in bacterial growth. In addition, phylogenetic tree was also constructed using 18s rRNA gene of A. niger and gene clusters of secondary metabolites were determined through bioinformatics tools.
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December 2019
Vol. 34, Iss. 2, pp. 105-238
