致病疫霉拮抗细菌WL2鉴定及其发酵液稳定性分析

为了明确WL2菌株在抑制致病疫霉(Phytophthora infestans)菌丝体生长及防治马铃薯晚疫病等方面特性,本试验采用对峙培养法和离体组织培养法检测WL2菌株对致病疫霉的抑制效果,评价发酵液抑菌作用稳定性;通过培养特征、生理生化检测以及16SrDNA序列分析对WL2菌株进行分类鉴定。结果表明,WL2菌活体、菌液和发酵液对致病疫霉菌丝体生长的抑制率分别为84.7%,86.8%和82.4%;16SrDNA序列分析表明WL2菌株为枯草芽孢杆菌(Bacillus subtilis),该菌发酵液经121℃高温处理后,抑菌率50%,经pH值2~12的条件处理后,发酵液抑菌率70%,在紫外灯(20 W)下照射12h后,发酵液抑菌率仍能达到77%以上,并且发酵液在4℃条件下可至少存放1年并保留其生防活性。这表明WL2菌株在开发成微生物制剂用于防治马铃薯晚疫病等方面具有突出的应用潜力。

Identification of antagonistic bacteria WL2 against Phytophthora infestans and stability analysis of its fermentation broth

In order to clarify the characteristics of WL2 strain in inhibiting Phytophthora infestans mycelia growth and preventing late blight of potato,the dual-culture method and in vitro tissue culture method were adopted to determine the inhibition effect and fermentation broth(FB)stability of WL2 strain.Meanwhile,WL2 strain was identified by culture characterization,biochemical test and 16S rDNA gene sequencing.The result showed that the inhibitory rates(IRs)of WL2 strain living bacteria,bacterial liquid and FB to P.infestans mycelia growth were 84.7％,86.8％ and 82.4％,respectively.In addition,16S rDNA gene sequencing identified WL2 strain as Bacillus subtilis.IRs of WL2 strain FB was more than 50％ after treatment with 121 ℃,over 70％ after the treatment of pH 2～12,and over 77％ after exposure even for 12 hours under UV lamp(20 W).Furthermore,FB of WL2 strain can be stored for at least 1 year under the condition of 4 ℃ with its biocontrol activity.These findings indicate that WL2 strain has great potential in the development of microbial agents for the prevention and control of potato late blight.