野生大豆内生细菌多样性及其杀线虫活性分析

为探明河北昌黎野生大豆内生细菌的多样性,寻找新的具有杀线虫活性的微生物资源,采用平板稀释法从野生大豆根、茎、叶等组织中分离内生细菌,结合形态特征以及16S rDNA基因序列进行比对分析,并对大豆孢囊线虫Heterodera glycines进行杀线虫活性比较.从野生大豆分离获得内生细菌180株,分属于7大类群:变形菌门α亚群、变形菌门β亚群、变形菌门γ亚群、厚壁菌门、放线菌门、酸杆菌门和疣微菌门,其中变形菌门α亚群和厚壁菌门为优势类群,分别占分离细菌总株数的48.9％和18.9％,野生大豆组织内生细菌Shannon-Wiener多样性指数为2.11 ～2.91.内生细菌Bacillussubtilis WSR93和B.megaterium WSR22菌株能明显地抑制大豆孢囊线虫卵的孵化,相对抑制率分别为97.9％和98.2％,对2龄幼虫也有较强的毒杀作用,校正死亡率分别为88.9％和90.9％.研究表明,野生大豆组织中内生细菌具丰富的多样性,其胞外分泌物中存在天然杀线活性物质.

Diversity and nematicidal activity of the endophytic bacteria in the wild soybean Glycine soja

In order to understand the diversity of the endophytic bacteria from tissues of wild soybean Glycine soja in Changli, and discover new strains with nematicidal activity, the endophytic bacteria were isolated from healthy root, stem, and leaf tissues using dilution plate counting method. The strains were identified according to the morphological characters combined with 16S rDNA sequences analysis, and the nematicidal activity of the strains against Heterodera glycines was also tested. The results showed that 180 endophytic bacteria strains isolated from different parts of wild soybean belonged to 7 bacterial groups, Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Firmicutes, Actinobacteria, Acidobacteria and Verrucomicrobia. The strains belonging to group Alphaproteobacteria and Firmicutes were the dominant endophytes in wild soybean, with 48.9% and 18.9% of total strains, respectively. The Shannon-Wiener index of endophyte bacteria in wild soybean was between 2.11 and 2.91. The endophyte bacteria Bacillus megaterium WSR22 and B.subtilis WSR93 inhibited egg hatching of soybean cyst nematode, with a relative inhibition rate of 97.9% and 98.2%, and had strong toxic effect against 2nd stage juveniles, with a corrected mortality rate of 88.9% and 90.9%. The study demonstrated that the species diversity of endophytic bacteria was abundant in tissues of wild soybean, and natural nematicidal products are existed in the fermentation fltrates of endophytic bacteria from wild soybean.