Optimization of culture conditions for growth and secondary metabolites production by Streptomyces sp. MFB27 using response surface methodology

This study aimed to optimize cultural conditions for the growth and production of bioactive metabolites by Streptomyces sp. strain MFB27, a promising yet underexplored microbial source. A key challenge was identifying and optimizing critical parameters to maximize metabolite yield, given the complex interactions among environmental factors. Various parameters, including culture media, inoculum size, incubation time, temperature, pH, and agitation rate, were investigated. To address this, an initial screening using a one-factor-at-a-time approach evaluated the effects of culture media, inoculum size, and incubation time. The results indicated that ISP2 medium and a 5-day incubation period maximized growth and metabolite production, while inoculum size showed no significant effect. The Box-Behnken Design was employed to further optimize temperature, pH, and agitation rate, revealing optimal conditions around 31 °C, pH 7.5, and 112 rpm, respectively. For optimal mycelial growth, the ideal combination was determined to be at 33 °C, pH 7.3, and agitation rate of 110 rpm. In contrast, secondary metabolite production was maximized at slightly different conditions: 31°C, pH 7.5, and agitation rate of 120 rpm for the extra-mycelial compounds, and 32°C, pH 7.6, and agitation rate of 112 rpm for the intra-mycelial compounds. Under these conditions, biomass and metabolites production were significantly enhanced, demonstrating the effectiveness of the optimization strategy and providing a validated framework for scaling up and further exploring the therapeutic potential of Streptomyces sp. MFB27. • Streptomyces strain from forest soil sample is a valuable source for discovering new bioactive metabolites. • Streptomyces MFB27 has potential for producing bioactive metabolites against Staphylococcus aureus ATCC 6538 • Optimum conditions were determined using one-at-a-time strategy and response surface methodology (RSM) with box benhken design (BBD) to maximize bioactive metabolite production