Optimization of Streptomyces sp.Fermentation Medium for Production of Alkylated Anthraquinone by Response Surface Methodology
[Objective]This study was aimed to optimize the fermentation conditions and medium composition of Streptomyces sp.WS-13394 by response surface methodology,so as to improve the production level of alkylated anthraquinones produced by the strain,and provide technical support for the application of this compound in animal husbandry.[Method]The optimal shake-flask fermentation conditions and the proper combination of carbon and nitrogen sources and mineral salts for the yield of alkylated anthraquinone produced by Streptomyces sp.WS-13394 were achieved through single-factor experiments.The significant factors affecting the yield of alkylated anthraquinone were fixed through Plackett-Burman design.The optimized medium for the yield of alkylated anthraquinone was achieved through the steepest ascending experiment,response surface design by fitting the significant factors with the yield of alkylated anthraquinone.[Result]The composition of the optimized medium for the yield of alkylated anthraquinone produced by Streptomyces sp.WS-13394 was as followings:Soluble starch 28.12 g/L,fish meal 10.00 g/L,yeast extract 6.34 g/L,CaCO3 0.71 g/L,MgSO4 0.50 g/L,and K2HPO4 0.50 g/L.The theoretical yield of alkylated anthraquinone based on the nonlinear regression formula was 408.35 mg/L.The optimal combination was applied to shake bottle fermentation test,and the yield of alkylated anthraquinone was 411.73 mg/L,which was 3.59 times higher than that before optimization(89.70 mg/L).[Conclusion]Response surface optimization was used to obtain the shaking flask fermentation medium formulation that significantly improved the yield of alkylated anthraquinone produced by Streptomyces sp.WS-13394.The results provided technical support for the studies of the antibacterial activity mechanism of this compound and the evaluation of its effect in animal models.