响应面法优化根结线虫生防真菌Snef5的发酵工艺

Ferment Optimization of Biocontrol Fungus Snef5 against Meloidogyne incognita by Response Surface Methodology

为提高生防真菌Simplicillium chinense Snef5的杀线虫活性,本研究采用响应面法对其发酵条件进行优化。首先,采用Plackett-Burman法筛选出有显著效应的3个因素:初始pH值、蔗糖和MgSO_4·7H_2O用量,而后通过Box-Benhnken设计和响应面分析法对其进行分析,获得了优化的最佳初始pH值为6.74,蔗糖含量4.19%,MgSO_4·7H_2O含量0.04%。经摇瓶和发酵罐发酵验证,该理论预测值与实测值无显著差异;优化后的发酵液杀线虫活性与原始发酵液相比,摇瓶发酵与30 L发酵罐产出的发酵液对南方根结线虫2龄幼虫的致死率分别提高了20.6%和21.3%,显示出较好的优化效果。试验结果对生防真菌的发酵及实际应用具有重要指导作用。

Simplicillium chinense strain Snef5 was screened as unique biological control fungi to plant nematodes in our previous research. In order to enhance its nematicidal activity, optimization of fermentation conditions were investigated for this fungus using response surface methodology. First, through Plackett-Burman screening experiments, three factors including the initial pH, the concentration of sucrose and MgSOa＇7H20 in the broth appeared to have significant effects on the fermentation. According to the results of Box-Benhnken design and response surface analysis, the optimal conditions for strain Snef5 fermentation were obtained with the initial pH 6.74, 4.19% sucrose and 0.04% MgSO4·7H20 in the medium. Fermentation experiments with shake flasks and 30 L fermentor verified that there was no statistical difference between the nematicidal activity forecasted by the model and that obtained in the tests. After optimizing the fermentation broth, Snef5 enhanced its nematicidal activity by exhibition of increasing the second juvenile （J2） mortality rate ofMeloidogyne incognita. Compared to the original fermentation broth, it showed 20.6% enhancement in the J2 mortality rate when using optimized broth in the flasks and 21.3% when using in the 30 L cylinders, respectively. Our research should have important implications for biocontrol fungi fermentation and application.