烟草青枯病生防真菌的分离鉴定与拮抗活性的初步研究

Isolation and Identification of Biocontrol Fungi against Tobacco Bacterial Wilt and Their Antagonistic Activity

为了获得对烟草青枯病菌(Ralstonia solancearum)具有较高拮抗活性的生防菌株,对其拮抗真菌进行了分离鉴定和活性筛选。采用系列稀释法和平板涂布法从黔江烟区土壤中分离到真菌116株。经滤纸片法测定,筛选出6株(约5.2%)对烟草青枯病菌有一定拮抗作用的菌株,并用最小抑制浓度(MIC)法测定了其中2株活性较高菌株3F03和7F06的拮抗活性。结果显示,菌株3F03和7F06的粗提物对烟草青枯病菌的半有效抑制浓度(IC50)分别为361.96μg/mL和102.67μg/mL。采用形态学观察结合ITS rDNA序列分析,鉴定其分别为烟曲霉(Aspergillus fumiga-tus)和浅黄新萨托菌(Neosartorya aureola)。

In this study,the antagonistic fungal strains against tobacco bacterial wilt were isolated and identified,in order to provide some research basis for biocontrol of the disease.In total,116 fungal isolates were obtained from rhizosphere of tobacco by serial diluting isolation.Six strains（about 5.2%） with certain antagonistic activity against the growth of wilt pathogen Ralstonia solancearum were found through the disc diffusion assay.The antagonistic activities of the extracts from two strong active fungal strains,3F03 and 7F06,were confirmed by MIC assay.The results showed that the IC50 of 3F03 and 7F06 against R.solancearum were 361.96 μg/mL and 102.67 μg/mL,respectively.These two active strains were further identified as Aspergillus fumigatus and Neosartorya aureola based on their morphology and ITS rDNA analysis.