青贮用拮抗黄曲霉并降解黄曲霉毒素菌株的筛选与鉴定

Screening and identification of a strain antagonizing Aspergillus flavus and degrading aflatoxin for ensiling

为筛选一株用于青贮的拮抗黄曲霉且能够降解黄曲霉毒素B1(AFB1)的芽孢杆菌菌株,本试验以香豆素为唯一碳源和能源进行菌株的初筛,以抑菌活性、AFB1降解率试验进行菌株的复筛。通过形态、生理生化特性以及16S r DNA序列分析对抑菌、毒素降解活性最好的菌株进行种属鉴定,并研究其对p H和温度的耐受性。结果表明:初筛获得45株能在以香豆素为唯一碳源和能源的培养基上生长的菌株,复筛发现N-1a对黄曲霉具有较强抑菌活性,对AFB1的降解率达到95%,并且对温度和pH具有良好的耐受性,最后鉴定N-1a菌株为枯草芽孢杆菌(Bacillus subtilis)。

The aim of the study was to screen a strain of Bacillus for ensiling which can antagonize Aspergillus flavus and degrade aflatoxin.Samples from various sources were screened by using coumarin as the sole carbon source and energy source.The bacteriostatic activity against Aspergillus flavus and AFB1 reduction rate were used for rescreening.The strain with better features was identified by morphological, physiological and biochemical properties together with phylogenetic analysis of 16 S r DNA sequences.The tolerance to p H and temperature was also studied.The results showed that a total of 45 strains were screened on the medium with coumarin as the sole source of carbon and energy. In the rescreening test,strain N-1 a was obtained, which had stronger antibacterial activity against Aspergillus flavus,and the highest degradation rate of 95%.Finally,N-1 a was identified to be Bacillus subtilis,and it was proved to have good tolerance to temperature and p H.