寡雄腐霉发酵参数优化及发酵液的生防效应

【目的】优化寡雄腐霉（Pythium oligandrum）发酵条件，为烟草黑胫病的生物防治奠定基础。【方法】采用单因素和正交试验研究寡雄腐霉的发酵参数及优化组合，并利用烟草黑胫病菌（Phytophthora nicotiana）、离体烟叶和盆栽烟苗验证发酵液的生防效应。【结果】随培养时间的延长，寡雄腐霉菌丝生物量持续增加，但发酵液对烟草黑胫病菌的抑制作用增加至峰值后降低。在不同培养基、温度、pH值和光照等条件下，寡雄腐霉的生物量越大，发酵液对烟草黑胫病菌的抑制作用愈强，二者的相关系数r =0.77**（n=16）。以黄豆饼粉为培养原料，初始pH值6.0、培养温度30℃、持续光照培养6 d所得的寡雄腐霉菌丝生物量最高，其发酵液对烟草黑胫病菌抑制率分别达到78.8%（菌丝生长）和52.9%（孢子萌发）。此外，寡雄腐霉发酵液显著降低离体烟叶和盆栽烟苗黑胫病的发病率和病情指数，对离体烟叶黑胫病的防效为69.3%—75.3%；对盆栽烟苗黑胫病的防效为55.0%—61.3%。【结论】在寡雄腐霉发酵过程中，选用适宜的培养基、pH值、温度、光照和发酵时间组合，可使发酵液抑制烟草黑胫病的效果达到最佳。

Fermentation Parameter Optimization of Pythium oligandrum and Biocontrol Effect of the Fermentation Broth

【Objective】 The objective of this study is to optimize the conditions of producing Pythium oligandrum fermentation broth and establish a theoretical foundation for biological control of tobacco black shank. 【Method】 The fermentation parameters were optimized through a single factor and orthogonal experiments, and the biocontrol effects of the fermentation broth were researched by tests on Phytophthora nicotiana, leaves of tobacco in vitro and potted plants in greenhouse. 【Result】 The biomass increased continuously with the culture time, but the inhibition rate increased to the peak then had downward trend. Under the condition of different culture media, temperature, initial pH, illumination time, the more the biomass of mycelia had, the stronger inhibition activity would express, and the correlation coefficients was 0.77**(n=16). Under the condition of culture medium composed of soybean cake powder, initial pH 6.0, 30℃, incubating 6 d and 24 h•d-1 illumination, the biomass of mycelia was the highest and the fermentation broth reached 78.8% for the growth of mycelia and 52.9% for the germination of spore on P. nicotiana. Moreover, the disease incidence and disease index were significantly decreased, the control effect was 69.3%-75.3% in the test on leaves of tobacco in vitro and 55.0%-61.3% in potted plants in greenhouse. 【Conclusion】 In the process of P. oligandrum fermentation, selecting the suitable conditions of the culture medium, pH value, temperature, illumination time and fermentation time, the best inhibition of tobacco black shank can be obtained.