Study on the fermentation optimization of Streptomyces sp.BF-1 and the antibacterial activity of the secondary metabolites

Objective To optimize the fermentation process with the aim of increasing the antibacterial substance in the Streptomyces sp.BF-1 secondary metabolites;Test the antibacterial activity of the metabolites in vitro.Methods Based on the index of antibacterial activity,the fermentation medium and conditions of Streptomyces sp.BF-1 were optimized by single-factor and orthogonal experiments;MIC values were detected by the agar dilution method.Results The optimal fermentation medium:starch 5 g·L-1,NH4Cl 5 g·L-1,soybean extract 15 g·L-1,MgSO4 0.25 g·L-1,seawater crystal 30 g·L-1;the optimal fermentation conditions: temperature 28℃,starting pH 7,inoculum concentration 5%;the MIC values of the metabolites to Pseudomonas aeruginosa was 640 μg·mL-1.Conclusion The secondary metabolites of Streptomyces sp.BF-1 showed significant antibacterial activity in vitro;the antibacterial activity of Streptomyces sp.BF-1 fermentation was 2.6 times higher than that before the optimization.