解淀粉芽孢杆菌BI_2的鉴定及其对黄曲霉的抑制作用

菌株BI2是从青贮玉米秸秆饲料中分离得到的一株革兰氏阳性芽孢杆菌.经16S rDNA序列分析,发现该菌株与解淀粉芽孢杆菌Bacillus amyloliquefaciens（NC_009725）的相似性达到99.6%;进一步结合Biolog及生理生化分析,将该菌株鉴定为解淀粉芽孢杆菌.以番茄叶霉病菌、黄瓜枯萎病菌等12种植物病原菌及部分霉菌、酵母、食品乳酸菌和人类致病细菌为指示菌进行抑菌实验.结果表明：BI2主要抑制丝状真菌,而对细菌无拮抗作用;BI2菌株生长36 h的上清液能明显抑制黄曲霉孢子萌发及其菌丝生长,抑制率分别达到67.4%和74.8%;而且该上清液经120℃高温处理20 min后对黄曲霉的抑制效果基本没有影响.

Identification of Bacillus amyloliquefaciens BI_2 and Its Antagonistic Activity Against Aspergillus flavus

The strain BI2 isolated from corn stalk of silage was G＋ bacillus.By means of 16S rDNA sequence analysis,morphological observation,physiological examinatio and Biolog assay,BI2 was identified as Bacillus amyloliquefaciens.Its 16S rDNA sequence was 99.6% to B.amyloliquefaciens in similarity.Its antagonistic experiments were conducted with 12 plant pathogens including Fulvia fulva,Fusarium oxysporum,yeasts,mold fungi,food lactobacilla and pathogenic bacteria.The results show that BI2 possessed evident inhibitory activity to filamentous fungi,but had no evident effect on bacteria.It was further found that the supernatant of its broth after 36 h fermentation significantly inhibited the conidial germination and hyphal growth of Aspergillus flavus with the inhibition ratios of 67.4% and 74.8% respectively.It was also found that its an-tagonistic activity of the supernatant was not decreased although it was treated even at 120 ℃ for 20 min.