响应面法优化北五味子褐斑病内生生防真菌淡紫拟青霉WG9发酵工艺及发酵产物稳定性研究

为提高北五味子内生生防真菌WG9发酵液对褐斑病病原菌的抑菌率,本研究采用单因素实验及响应面法对其发酵条件进行优化。首先采用单因素实验,以发酵时间（h）、发酵温度（℃）、摇床转速（r/min）及初始pH为考察指标,测定对病原菌的抑菌率及生防真菌WG9的菌丝体生物量,以获取单因素实验的最优值,然后使用Box-Behnken实验设计及响应分析法对其进行分析,得出的最佳发酵工艺为：发酵时间127.2h（5.2d）,发酵温度25.09℃,摇床转速121.49r/min,初始pH 6.25,该条件下发酵液抑菌率可达51.20%。经验证实验得发酵液抑菌率为(50.86±0.097)%,与预测值的相对误差较小且与实验结果拟合程度高;同时测定了温度、pH、紫外线照射及贮存时间对发酵液稳定性的影响,结果表明该菌株发酵液稳定性较好,除强酸强碱外,其他条件对其稳定性影响不大。本研究为生防真菌的产业化奠定了理论基础,同时也为其他生防菌的发酵工艺提供数据参考。

Response surface methodology for optimizing fermentation process of the endophytic fungus Purpureocillium lilacinum WG9 preventing Schisandra chinensis brown spot disease

Fermentation conditions of Schisandra chinensis endophytic fungus Purpureocillium lilacinum WG9 against the brown spot pathogen Phoma glomerata were optimized by use of single factor experiment and response surface method. Fermentation duration (h), fermentation temperature (°C), shaker speed (r/min) and initial pH are used as the inspection indicators. Inhibition rate of pathogenic fungus and mycelial biomass of the biocontrol fungus WG9 are determined. The optimal value of the single factor experiment are examined by using Box-Behnken experimental design and response analysis method. The best fermentation process obtained is: fermentation duration of 127.2h (5.2d), fermentation temperature of 25.09°C, shaker speed of 121.49r/min and initial pH of 6.25. Under these conditions, the anti-fungal rate of the fermentation broth can reach 51.20%, actually (50.86±0.097)% obtained by verification experiment, and the relative error of predicted value is small and the degree fitting the experimental results is high. The effects of temperature, pH, ultraviolet radiation and storage time on the stability of fermentation broth are determined and the results show that the fermentation broth has good stability. Except for strong acid and strong alkali, other conditions have little effect on its stability. This research provides a reference for large-scale industrialized fermentation of the fungus.