降解黄曲霉毒素B_(1)菌株的筛选鉴定及降解条件优化

Screening and identification of aflatoxin B_(1)degrading strains and optimization of degrading conditions

【目的】从分离源中筛选得到黄曲霉毒素B_(1)(aflatoxin B_(1),AFB_(1))高降解率的菌株并进行鉴定,优化菌株降解AFB 1的条件。【方法】以青贮饲料、泡菜液及腌酸菜为分离源,以香豆素为唯一碳源的培养基进行菌株初筛。采用高效液相色谱法检测AFB_(1)含量,以高AFB_(1)降解率进行复筛,对所得菌株进行鉴定,确定菌株名称。以AFB_(1)降解率为指标,探明发酵时间、初始pH、接种量及AFB_(1)浓度对菌株降解AFB_(1)的影响,通过正交试验进行降解条件优化。【结果】初筛共筛选出16株可以利用香豆素的菌株,复筛时QC7有最高降解率,为86.00%,经鉴定为空气芽孢杆菌(Bacillus aerius)。当AFB_(1)质量浓度为0.2μg/mL时,其最优降解条件为发酵时间72 h、初始pH 6.5、接种量5%。最高降解率为89.41%。【结论】筛选得到了对AFB_(1)有较佳降解能力的菌株,通过条件优化,提高了菌株对AFB_(1)的降解率,为后续降解机制探究提供了基础。

[Objective]To screen and identify the strains with high degradation rate of aflatoxin B_(1)(AFB_(1))from the isolation sources,and optimize the degradation conditions of AFB_(1).[Methods]Silage,pickle liquor and pickled sauerkraut were selected as the separation sources,and the strain was screened in the medium with coumarin as the only carbon source.The content of AFB_(1)was detected by high performance liquid chromatography,the strain was identified and the name of the strain was determined by high degradation rate of AFB 1.With the degradation rate of AFB_(1)as the index,the effects of fermentation time,initial pH,inoculation amount and AFB_(1)concentration on the degradation of AFB_(1)were investigated,and the degradation conditions were optimized by orthogonal test.[Results]A total of 16 strains that could use coumarin were selected in the initial screening,and the highest degradation rate of QC7 was 86.00%during the re-screening,which was identified as Bacillus aerius strain.When the mass concentration of AFB_(1)was 0.2μg/mL,the optimal degradation conditions were fermentation time 72 h,initial pH 6.5 and inoculum size 5%.The highest degradation rate was 89.41%.[Conclusion]In this study,strains with better ability to degrade AFB 1 has been screened,and the degradation rate of AFB_(1)has been improved by optimizing the conditions.It provides a basis for further research of degradation mechanism.