一株辣椒青枯病菌拮抗内生细菌的筛选鉴定与发酵条件优化

【目的】筛选对辣椒青枯病菌生防效果较好的内生细菌,丰富辣椒青枯病的生物防治菌种资源,为生防制剂的研发生产及进行大田生物防治提供理论依据。【方法】在湖南长沙青枯病发病区采集健康的辣椒植株样品,通过平板稀释分离和划线纯化方法获得内生细菌后采用琼脂扩散法进行拮抗作用测定,筛选出拮抗青枯病菌效果较好的内生细菌,然后通过菌体的形态结构观察、生理生化特性试验及16S r DNA序列同源性分析,对筛选出的细菌进行鉴定,采用正交试验对其发酵条件进行优化试验。【结果】筛选出一株对青枯病菌拮抗作用效果好的内生细菌L009,通过对其形态学、生理生化特性鉴定和16S r DNA序列的系统发育鉴定,该菌株为解淀粉芽孢杆菌（Bacillus amyloliquefaciens）。通过正交试验,确定该菌株的最佳发酵条件为：玉米淀粉8%、豆饼粉6%、Na Cl 0.5%、Ca CO30.5%、K2HPO40.08%、p H 7.0、72h、28℃、180 r/min转速。【结论】L009菌株对辣椒青枯病菌具有较好的拮抗作用,具有作为生防制剂的潜力。

Isolation and identification of an antagonistic endophytic bacteria strain against Ralstonia solanacearum in pepper and its optimal fermentation conditions

【Objective 】Qualified antagonistic endophytic bacteria strains against Ralstonia solanacarum were screened and fungi resources for Ralstonia solanacarum bio-control in pepper were enriched to provide theoretical ref-erences for producing bio- control agents and executing field bio- control. 【 Method 】 Antagonistic endophytic bacteria strains with inhibiting effect on pepper R. solanacearum were isolated from healthy plants of pepper in bacterial wilt areas in Changsha of Hunan by pour plate,streak purification and agar diffusion method. The bacterial species were identified by morphology observation, physiological and bio-chemical tests and the sequence analysis of the 16 S r D-NA. Orthogonal design method was employed to optimize the fermentation conditions. 【Result 】One antagonistic endophytic bacteria strain L009 with obviously inhibiting effect on pepper R. solanacearum was selected from a healthy pepper plant. Based on the morphology, culture, characteristics, physiological and biochemical tests and 16 S r DNA analysis, L009 was identified as Bacillus amyloliquefaciens. Orthogonal experiment showed that the optimum culture medium was 8% corn starch, 6% soybean powder, 0.5% Na Cl, 0.5% Ca CO3 and 0.08% K2HPO4. Culture conditions were p H of 7.0, fermentation time of 72 h, temperature of 28 ℃ and shake rotation of 180 r/min. 【Conclusion 】L009has continuous inhibiting effect on pepper R. solanacearum,manifesting its great potential as bio-control agents.