野生型桑树内生细菌的多样性分析及ME0717菌株的抑菌活性测定

从多年生野生鲁桑的枝条中分离出190株内生细菌,并分析其多样性指数(H)、丰度(D)、均匀度(J),发现在不同发育时间的桑树枝条中,内生细菌的种类、数量和多样性指数明显不同,枝条发育时间越长,越不利于内生菌的生长,而1年生枝条最有利于内生细菌的生长。分离得到1株优势内生细菌,命名为ME0717。经培养性状观察、形态鉴定、染色反应等生化特性测定以及16S rDNA序列分析,鉴定ME0717为枯草芽孢杆菌(Bacillus subtilis)。ME0717菌体和发酵液对桑炭疽病菌(Colletotrichum morifolium Hara.)、桑漆斑病菌(Myrothecium roridum Todeet Fr.)的菌丝生长和孢子萌发均有明显的抑制作用,随着培养时间的延长,菌株的发酵液对两种病原菌的菌丝生长和孢子萌发的抑制作用增强。

Biodiversity of Endophytic Bacteria in Wild Mulberry Tree and Inhibition Effect of ME0717 Strain on Pathogens

One hundred and ninety Endophytic bacteria strains were isolated from the branches of wildtype Lu mulberry. The Shannon diversity index (H), richness (D) and eveness(J) of the isolated bacteria strains were analyzed. The results showed that the species, quantity and diversity index of endophytic bacteria were different at the different development stages of branches. The age of branches brought about negative effect on the growth of endophytic bacteria. The annual branch was the most suitable for the growth of endophytic bacteria. A superior strain of endophytic bacteria, named as ME0717, was isolated and identified as Bacillus subtilis by cultivating features, staining characteristics and 16S rDNA sequence analysis. The strains and fermentation broth of ME0717 could significantly inhibit the mycelia growth and spores germination of Colletotrichum morifolium and Myrothecium roridum. Moreover, the inhibition effect of the fermentation broth on the mycelia growth and spores germination of the two pathogens increased along with the fermentation time extension.