黄曲霉毒素B_1降解菌的筛选及鉴定

Isolation and Identification of Aflatoxin B_1 Degradation Strains

目的:在易被黄曲霉毒素B_1(AFB_1)污染的不同环境中,筛选能够降解AFB_1的菌株。方法:以香豆素为唯一碳源和能源进行AFB_1降解菌株的初筛,得到生长良好的菌株,分别与AFB_1标品(2.5μg/m L)共同作用进行复筛。对降解率最高的菌株通过形态以及16S r DNA序列分析,进行初步鉴定;并对胞外粗提液、菌细胞、胞内裂解物降解AFB_1进行研究。结果:从腐烂朽木中筛选出的菌株XY1降解AFB_1能力达71.91%。根据XY1菌株形态、16S r DNA序列同源性分析,初步确定菌株XY1为克雷伯氏菌(Klebsiella sp.)。胞外粗提液降解率为70.23%,菌细胞悬液降解率为8.26%,胞内裂解物的降解率为3.18%,表明菌株XY1的降解活性与胞外粗提液有关。结论:筛选到能高效降解AFB_1的克雷伯氏菌(Klebsiella sp.)XY1,XY1降解毒素的活性物质主要存在于胞外粗提液。

Objective：The aim of this research was to isolate aflatoxin B1 （AFB1）- degrading strains from different habitats which easily contaminated by aflatoxin Bl.Methods：Using cumarin as the carbon source and energy to have the first screening. The strains that could grow in the medium with coumarin carbon source were detected for their degradation of AFB1 ability by addition of AFB1 （2.5 μg/mL）.Among the grow well strains which had the highest degradation rate was preliminarily identified according to its morphological and analysis of its 16S rDNA sequence. Degradation of AFB1 by cell-free supernatant, strain cells, and intracellular cell extracts of strain.Results ： Strain XY1, obtained from decay deadwood （poplar） could reduce AFB1 by 71.91% after incubation.XY1 was preliminary identified to be KlebsieUa sp.with morphology and 16S rDNA gene sequence The cell-free supernatant（70.23% ）of isolate XY1 was able to degrade AFB1 effectively ,whereas the viable cells（ 8.26% ）and cell extracts（3.18% ）were far less effective. Conclusion： An AFB1 -degrading strain XY1 was isolated from decay deadwood （poplar） and identified as Klebsiella sp..The activive component of AFB1 degradation was mainly in the cell-free supernatant of XY1.