桃褐腐病生防细菌JY-d1种类鉴定及其对桃褐腐病菌生防机制研究

Identification of biocontrol agent JY-d1 and biological control mechanism of this bacterium against peach fruit brown rot pathogen Monilinia fructicola

通过平板对峙培养法测定拮抗细菌JY-d1抑菌谱,并在鲜桃果实上测定对褐腐病的防病效果。结合生理生化性状及gyrB基因序列同源性分析鉴定生防细菌JY-d1的种类,并利用MALDI-TOF MS初步分析JY-d1产生的抗菌物质种类。结果表明:生防细菌JY-d1抑菌谱广,对桃褐腐病菌的拮抗作用最强,抑菌带宽达到9.3 mm。以细菌悬浮液处理桃果实,对桃褐腐病防病效果可达70%左右。通过传统分类法和分子分类法将菌株JY-d1鉴定为解淀粉芽孢杆菌(Bacillus amyloliquefaciens)。PCR扩增结果表明,JY-d1基因组中存在编码丰原素的fenB和伊枯草菌素的ituD基因。质谱图显示该抗菌物质包含C15-IturinA、C16-IturinA和C17-IturinA,且伊枯草菌素粗提物浓度达2.34 mg·mL^(-1)时可完全抑制分生孢子萌发,说明该菌具有良好的生防潜力。

The dual culture and the detached peach were used to test the inhibition spectrum and control effect of strain JY-d1. MALDI-TOF MS was performed to identify and characterize the antimycotic peptides from the culture broth of the bacterium. The results showed that the biocontrol agent JY-d1 displayed a wide inhibition spectrum and the strongest antagonistic activity to Monilinia fructicola. The width of inhibition zone reached 9.3 mm. The control effect was 70% when peaches were treated with cell suspensions of JY-d1. The strain JY-d1 was identified as B.amyloliquefaciens based on traditional and molecular classifications. The PCR analysis suggested the presence of biosynthetic operons for ituA and fenB, coding for iturin and fengycin, respectively in the genomic DNA of JY-d1. MALDI-TOF MS detection revealed the presence of iturinA(C_(15)-C_(17)) isoforms in the antifungal compoundss produced by strain JY-d1. In addition, the germination of spores was completely inhibited when the concentration of iturinA extract was added with 2.34 mg·mL^(-1), suggesting the biocontrol potential of JY-d1.