Screening and identification of aflatoxin B1 degrading strains and optimization of degrading conditions
[Objective]To screen and identify the strains with high degradation rate of aflatoxin B1(AFB1)from the isolation sources,and optimize the degradation conditions of AFB1.[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 AFB1 was detected by high performance liquid chromatography,the strain was identified and the name of the strain was deter-mined by high degradation rate of AFB1.With the degradation rate of AFB1 as the index,the effects of fermentation time,ini-tial pH,inoculation amount and AFB1 concentration on the degradation of AFB1 were investigated,and the degradation condi-tions 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 aeri-us strain.When the mass concentration of AFB1 was 0.2 μg/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 AFB1 has been screened,and the degradation rate of AFB1 has been improved by optimizing the condi-tions.It provides a basis for further research of degradation mechanism.
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