一株抑真菌、对甜菜夜蛾高效的苏云金芽胞杆菌菌株

The Characterization of an Antagonistic Bacillus thuringiensis Strain Against Crop Pathogens and Pests

为了扩大苏云金芽胞杆菌的杀虫谱及生防范围,通过抑真菌和杀虫生物活性测定,筛选到一株抑真菌并对甜菜夜蛾高效的菌株Bt519-1。此菌株对所测试的小麦赤霉、黄瓜灰霉等8种真菌都有不同程度的抑制作用,且完全抑制这些真菌孢子的萌发。通过室内生物测定发现该菌株对甜菜夜蛾具有很高的杀虫活性,半致死浓度(LC50)仅为5.5μg/mL。经特异引物检测,证明该菌株含有6种杀虫蛋白基因:cry1Aa、cry1Ab、cry1Ac、cry1I、cry2和vip3A。经SDS-PAGE分析,Bt519-1菌株分别产生分子量大约为135 kD～130 kD、95 kD、80 kD、70 kD和65 kD～60 kD的几种杀虫晶体蛋白。在有无几丁质的培养基中都能产生较高活性的几丁质酶。试验证明苏云金芽胞杆菌Bt519-1是一株既杀虫又拮抗真菌的多功能生防菌株。

Bacillus thuringiensis strain 519-1 was tested for the antagonistic activity against the growth of hyphae of eight fungi including Aspergillium niger,Botrytis cinerea,Fusarium graminearum,Fusarium oxysporum,Penicillium chrysogenum,Physalospora piricola,Rhizoctonia solani,Rhizopus nigricans.It could notably inhibit sporangia germination of all the tested fungi.The culture of 519-1 exhibited high toxicity against Spodoptera exigua and Helicoverpa armigera,with LC50 values of 5.5 μg/mL and 12.5 μg/mL,respectively.PCR analysis with specific primers showed that the strain contained five insecticidal protein encoding genes： cry1Aa,cry1Ab,cry1Ac,cry1I,cry2 and a vegetative insecticidal protein gene,vip3A.Cry proteins with molecular weight about 135 kD～130 kD、95 kD、80 kD、70 kD and 65 kD～60 kD were detected using SDS-PAGE.The chitinase was expressed from the strain independent of any chitin.The results showed that Bt519-1 was a strain which had high activities of broad-spectrum antagonistic and high insecticidal toxicity against lepidopteran pests.