亚麻立枯病拮抗菌的筛选、生防效果及发酵条件优化

Screening, biocontrol effect and optimization of fermentation conditions of an antagonistic bacteria against Flax Rhizoctonia solani

摘要:

【目的】从健康亚麻植株的根际土壤中筛选对亚麻立枯病菌具有较强抑菌作用的拮抗菌，优化其产生抑菌活性物质的发酵条件，为其生防利用奠定基础。【方法】采用稀释平板涂布法和对峙培养法进行拮抗菌的筛选；根据菌株形态学特征、生理生化特性以及16S rRNA基因序列分析对其进行鉴定；利用温室抗病实验确定其生防效果；通过单因素实验和均匀设计实验优化其发酵条件。【结果】分离筛选到一株对亚麻立枯病菌具有显著拮抗作用的细菌HXP-5，且其对另外7种植物病菌真菌均有拮抗作用；鉴定菌株HXP-5为枯草芽孢杆菌；温室抗病实验结果表明其生防效果可达71.22%；其产生抑菌活性物质的最佳发酵条件为：葡萄糖为2.3%，胰蛋白胨+酵母粉(3:1)为0.25%，NaCl为0.18%，发酵时间为72 h，发酵温度为27 °C，转速为210 r/min，250 mL摇瓶装液100 mL，接种量为1.7%。【结论】经鉴定，对亚麻立枯病病菌具拮抗作用的菌株HXP-5为枯草芽孢杆菌，且对亚麻立枯病具有较强的防治效果，发酵条件进行优化后其对亚麻立枯病病原菌显示出更强的拮抗作用。

Abstract:

[Objective] To isolate and screen antagonistic strains with strongly inhibitory activity on Rhizoctonia solani (Linum usitatissimum L.) from the rhizosphere soil of healthy flax. [Methods] Antagonistic strains were screened out through plate coating and dual culture method. Strains were identified by morphological, physiological and biochemical characteristics and 16S rRNA gene sequence analysis and their biocontrol effect were determined by greenhouse experiment. The fermentation condition was optimized by single factor and Uniform design experiment. [Results] Strain HXP-5 showed strongly inhibitory activity on R. solani (Linum usitatissimum L.) and also antagonistic?effect against other seven phytopathogens. Strain HXP-5 was identified as Bacillus subtilis. Greenhouse experiment showed that the control efficiency were 71.22%. The optimized culture conditions produced antimicrobial active substances of strain HXP-5 were liquid volume 100 mL in 250 mL flask, 210 r/min at 27 °C, inoculation size of 1.7% for 72 h with a medium of 2.3% glucose, 0.25% tryptone+yeast extract (3:1), 0.18% NaCl. [Conclusion] The antagonistic strain HXP-5 to R. solani (Linum usitatissimum L.) was identified as B. subtilis. And it has a stronger effect on biocontrol of Flax Rhizoctonia solani. HXP-5 strain shows stronger antagonistic action to R. solani (Linum usitatissimum L.) under optimized fermentation conditions.