嗜线虫杆菌发酵液对苎麻疫霉的抑制作用

THE ANTIBIOSIS OF XENORHABDUS SPP. AGAINST PHYTOPHTHORA BOEHMERIAE

用室内平板抑菌法测定了８株嗜线虫杆菌对苎麻疫霉的抑制效果。结果表明：嗜线虫杆菌对苎麻疫霉菌丝有较强的抑制生长作用，所有株系的发酵液稀释５倍时，对苎麻疫霉的抑菌率均达１００％；稀释１０倍时，抑菌率达９５％以上的株系占８７．５％；稀释１５倍，抑菌率在８０％以上的株系占５０％。不同的嗜线虫杆菌对苎麻疫霉的抑菌作用存在很大差异，抑菌作用最强的是Ｘ．ｐｏｉｎａｒｉ的ＮＣ５１３和ＮＣ３２株系，其ＥＣ５０分别为０．０８％和０．１３％，其次是Ｘ．ｎｅｍａｔｏｐｈｉｌｕｓ的ＢＪ和Ａ２４株系，ＥＣ５０分别为０．４０％和０．８８％，其它株系ＥＣ５０在１．９４％～６．０３％之间不等。嗜线虫杆菌发酵液对苎麻疫霉有溶菌和抑制菌丝生长的作用，经发酵液处理后的苎麻疫霉菌丝扭曲、分支增多、分支顶端膨大，甚至菌丝胞壁破裂，原生质外溢。

This paper reported the antibiosis of 8 strains of Xenorhabdus spp. against Phytophthora boehmeriae by means of laboratory plate inhibiting test and the way of antibiotic action of the A24 strains against the P.boehmeriae. The result showed that different species have different antibiotic effects against P.boehmeriae, when fermented liquid was diluted 5 times, 100% inhibition occurred to all test strains; diluted 10 times, 87.5% to 95% inhibition; dilut 15 times, 50% to 80% inhibition. Strains NC513 and NC32 were best ones, the EC50 being 0.08% and 0.13% respectively; BJ and A24 were next, EC50 being 0.40% and 0.88% respectively, while the EC50 of other strains ranked from 194%-6.04%. Inhibited hyphae shape was observed by gradually diluting fermented liquid, it was found that hyphotroma of P.boehmeriae twisted, the abnormal branching increased, the hyphal tip inflated, the hyphal wall broke and the cytoplasm leaked.