Optimization of the Fermentation Medium with Streptomyces aureofaciens

Streptomyces aureofaciens produce tetracyclines,while antibiotics are secondary metabolites of microorganisms.The yield is closely related to the composition of the medium and culture conditions.This article first investigated the carbon and nitrogen sources by single factor experiments which are necessary to the growth of S.aureofaciens.On this basis,orthogonal design(L9(34))was adopted to optimize the fermentation medium of S.aureofaciens.Its four factors were corn starch,soybean flour concentration and ammonium sulfate concentration,yeast extract.Experimental results show that biological effect of the best medium optimized by using the experimental measured cylinder-plate method fermentation of liquid in the tested strains is 183.2 μg/mL.Orthogonal range analysis of the results indicates that,in yeast fermentation medium,the mass fraction of the yeast extract affects the yield of antibiotics most,followed by corn starch and the concentration of soybean powder,ammonium sulfate on the production of antibiotics in the least.Selection to the best culture medium composition: corn starch 100.0 g/L,soy flour 50.0 g/L,ammonium sulfate 6.0 g/L,yeast extract 4.0 g/L.