芒果蒂腐病拮抗放线菌A10和A17的分离、鉴定和特征化研究

Isolation,identification and characterization of antagonistic actinomycetes A10 and A17 against Botryodiplodia theobromae

为丰富芒果蒂腐病拮抗菌资源,寻找替代化学杀菌剂的无毒无污染的采后防治方法,使用平板稀释法、划线纯化法、纸片扩散法从芒果树根际土壤中分离筛选对蒂腐病有拮抗作用的放线菌,明确其分类地位,优化其发酵条件,测试活体防效。共筛选到两株对采后芒果蒂腐病菌可可球二孢(Botryodiplodia theobromae Pat.)有较强抑菌活性的拮抗放线菌A10和A17,其中A17对另一种引起芒果蒂腐病的病原菌芒果拟茎点霉也有拮抗作用。经形态特征、生理生化特性和分子鉴定初步判断,2株放线菌均为链霉菌属(Streptomyces)。A10菌株的发酵培养基和发酵条件优化后为:2.5%乳糖,2.0%蛋白胨,初始pH 8.0,摇床转速200 r·min^-1,培养时间120 h;A17菌株的发酵培养基和发酵条件优化为:2.0%可溶性淀粉,2.0%蛋白胨,初始pH 7.0,摇床转速200 r·min^-1,培养时间120 h。活体实验中,第4天时,无菌水处理的对照组果实发病率和发病指数分别为81.7%、52.5,A10处理组分别为43.3%、21.7,A17处理组分别为36.7%、17.5,450 mg·kg^-1咪鲜胺处理组分别为16.7%、12.2,说明两株菌均对蒂腐病的发生和病斑扩展有一定的抑制效果,且A17对病斑扩展的抑制效果和450 mg·kg^-1咪鲜胺处理无显著差异。研究表明,这两种菌株均对蒂腐病菌有一定的拮抗作用,可进一步深入研究。

In order to enrich the antagonistic and antibacterial resources of mango stem-end rot and find a non-toxic and non-polluting post-harvest control method instead of chemical fungicide,plate dilution method,scribing purification method and paper diffusion method were used to separate and screen the antagonistic actinomycetes against Botryodiplodia theobromae from mangrove rhizosphere soil.Their taxonomic status was identified,the fermentation conditions were optimized,and the biological control effect was tested.A total of two antagonistic actinomycetes A10 and A17 with strong antibacterial activity against postharvest mango rot fungus(Botryodiplodia theobromae Pat.)were screened.According to the morphological characteristics,physiological and biochemical characteristics and molecular identification,the two actinomycetes were all Streptomyces.The fermentation medium and fermentation conditions of A10 strain were optimized as follows:2.5%lactose,2.0%peptone,initial pH 8.0,shaking speed 200 r·min^-1,culture time 120 h.The fermentation medium and fermentation conditions of A17 strain were optimized as follows:2.0%soluble starch,2.0%peptone,initial pH 7.0,shaking speed 200 r·min^-1,culture time 120 h.In vivo experiment,on the 4th day,the incidence and disease index of the control group treated with sterile water were 81.7%and 52.5,respectively,43.3%and 21.7 in the A10 group,36.7%and 17.5 in the A17 group,and 16.7%and 12.2 in the 450 mg·kg^-1 prochloraz group.Both strains had a certain inhibition effect on the occurrence and expansion of the disease spot,and A17 had a certain inhibition effect on the expansion of the disease spot.There was no significant difference between the inhibitory effect of A17 and that of 450 mg·kg^-1 prochloraz.The results showed that the two strains had some antagonistic effect on the pathogen,which could be further studied.