Improved Antibiotic Activity from Streptomyces monomycini strain RVE129 Using Classical and Statistical Design of Experiments

Firew Elias^1,3, Sudhamani Muddada¹, Diriba Muleta^2*and Belachew Tefera³

¹Koneru Lakshmaiah Education Foundation, Department of Biotechnology, Guntur, India

²Environmental Biotechnology Unit, institute of Biotechnology, Addis Ababa University, Ethiopia.

³Animal Products Veterinary Drugs and Feed Quality Control Centre of Ethiopia

Corresponding Author E-mail: firew2010@gmail.com

Abstract: Many bioactive secondary metabolites with intriguing antibacterial, antiviral, and anticancer properties have been produced by Streptomyces species. The objective of this work is to use conventional and statistical techniques to improve the antibiotic production medium of Streptomyces monomycini RVE129, which was isolated from rhizospheric soil in Hawassa, Ethiopia. The main media components were chosen using the one factor at a time method and the Plackett-Burman design, which was then, further, optimized using the Box-Behnken Design for increased antibiotic production. On  ISP4 medium (10 g/L starch, 1 g/L NaCl, 1 g/L MgSO₄.7H₂O, 2 g/L (NH₄) 2SO₄, 2 g/L CaCO₃and 1 g/L K₂HPO_4, 0.1 g/L  FeSO₄·7H₂O, 0.1 g/L  MnCl₂·4H₂O, 0.1 g/L  ZnSO₄·7H₂O), S. monomycini RVE129 produced the greatest amount of antibiotics. Starch and soybean meal were found to be the best sources of carbon and nitrogen for the strainRVE129. During the eighth day of incubation under shaking conditions, the best conditions for antibiotic synthesis were determined at a temperature of 30°C and a pH of 7.5. Plackett-Burman design identified K₂HPO₄, starch, and soybean meal as having the highest influence on antibiotic synthesis with a confidence level above 95%. The yield of producing antibiotics increased by 24.30% when the concentration of critical variables was further improved by using the Box-Behnken Design of the Response Surface approach. The optimum concentration was 20 g/L starch, 7.5 g/L s oybean meal, and 1.25 g/L K₂HPO₄. To the best of our knowledge, this is the first investigation into medium optimization for the production of the antibiotic from S. monomycini RVE129.

Keywords: Antimicrobial metabolites; Biomass; Optimization; Streptomyces monomycini

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