Screening and Identification of Aflatoxin B₁ Degradation Strains

The chemical structure of aflatoxins (AFs) is very similar to coumarin.It has strong toxicity,carcinogenicity,and is an unavoidable pollutant in feed and foods.It is urgent to develop effective and environmentally friendly detoxification methods for degrading aflatoxins.In order to isolate bacteria with AFs degradation activity,screening was carried out using coumarin,a structural analogue of AFs,as the sole carbon source.As a result,one strain (HH-1) with high degradation rate (91.86%) was obtained.16S rDNA gene sequencing confirmed it as a strain of Bacillus licheniformis.Broth culture of HH-1 were divided into different components including culture supernatant and bacterial cell.The results indicated that the activity of aflatoxins degradation mainly existed in the culture supernatant of strain HH-1 rather than in bacterial cells.High temperature and protease K treatments suggested that its degradation activity was largely due to the action of extracellular enzymes.The degradation products P₁ and P₂ of AFs were also detected by high performance liquid chromatography.