一株番茄青枯病菌拮抗细菌的筛选、发酵条件优化及田间小区防效

背景]番茄青枯病是由青枯劳尔氏菌(Ralstonia solanacearum)引起的一种土传细菌性病害,该病原菌严重影响番茄的生产。目的]筛选番茄青枯病的生防细菌,并将其用于病害防治。方法]采用抑菌圈法、琼脂扩散法从湖南衡阳青枯病发病田的健康番茄根际土壤筛选对青枯劳尔氏菌具有较强拮抗能力的菌株,通过形态学观察、生理生化试验、16S rRNA基因和gyrA基因测序分析确定其分类地位;以单因素试验和正交试验对发酵条件进行优化;通过田间小区试验初探其防效。结果]筛选的菌株TR-1被初步鉴定为贝莱斯芽孢杆菌(Bacillus velezensislezensis);菌株TR-1最佳培养基配方(g/L):可溶性淀粉20.0,大豆蛋白胨10.0,磷酸氢二钾5.0;最佳发酵条件:pH6.0-7.0,温度30-33℃,摇床转速160 r/min,发酵时长48 h,优化后TR-1无菌发酵上清液对青枯菌抑菌圈直径达2.95 cm,约为优化前的2倍;其田间小区防效为60.30%。结论]通过对菌株TR-1发酵条件进行优化可大大提升其发酵液抑菌效果,而且菌株TR-1在田间小区试验中对番茄青枯病防效优...

Screening, fermentation condition optimization, and field control effect evaluation of an antagonistic bacterium against Ralstonia solanacearum

Background]Tomato bacterial wilt is a soil-borne bacterial disease caused by Ralstonia solanacearum,which severely restricts the production of tomato.Objective]To screen out an antagonistic bacteriumand apply it to biocontrol of tomato bacterial wilt.Methods]We used the inhibition zone method and agar diffusion method to screen the bacterial strains with strong antagonistic effect against R.solanacearum from the rhizosphere soil of healthy tomato plants in a field with bacterial wilt in Hengyang,Hunan.The strain was identified by the observation of morphological characteristics,physiological and biochemical tests,and sequence analysis of 16 S rRNA gene and gyrA gene.The fermentation conditions were optimized by single factor test and orthogonal test.The control effect was investigated by field experiment.Results]Strain TR-1 with a significant antagonistic effect against R.solanacearum was screened out and preliminarily identified as Bacillus velezensis.The optimized medium for TR-1 was composed of 20.0 g/L soluble starch,10.0 g/L soybean peptone,and 5.0 g/L K2 HPO4.The optimum fermentation conditions:pH 6.0-7.0,30-33°C,160 r/min,and 48 h.The inhibition zone of the sterile fermentation supernatant of TR-1 cultured under the optimized conditions against R.solanacearum showed a diameter of 2.95 cm,which was about twice the size before.TR-1 showed the control effect of 60.30%in the field experiment.Conclusion]The optimization of fermentation conditions greatly improves the inhibition effect of TR-1 fermentation broth.The strain has a good control effect on tomato bacterial wilt in the field experiment and demonstrates the potential to be applied in the biocontrol of this disease.