Characterization of a aflatoxin B1-degrading enzyme (TV-AFB1D) and its application in the AFB1 degradation of contaminated rice .

Aflatoxin B (AFB) contaminates rice during harvest or storage and causes a considerable risk to human and animal health. In this study, AFB-degrading enzyme (TV-AFBD) gene recombinantly expressed in engineered BL21 (DE3) and . The TV-AFBD enzymatic characteristics and AFB degradation efficiency in contaminated rice were investigated. Results showed that the size of recombinant TV-AFBD expressing in BL21 (DE3) and was appropriately 77 KDa. The kinetic equation of TV-AFBD was  = 0.01671 + 1.80756 (  = 0.994,  = 9.24 mM, and  = 553.23 mM/min). The and / values of TV-AFBD were 0.07392 (s) and 8 M s, respectively. The AFB concentration of contaminated rice decreased from 100 μg/ml to 32.6 μg/ml after treatment at 32°C for 5 h under the catabolism of TV-AFBD. engineered strains carrying aldehyde oxidase 1 () and 35 S ( 35 S) promoters caused the residual AFB contents, respectively, decreased to 3.4 and 2.9 μg/g from the initial AFB content of 7.4 μg/g after 24 h of fermentation using AFB-contaminated rice as substrate. The AFB degradation rates of engineered strains carrying and promoters were 54 and 61%, respectively. Engineered strains integrated with TV-AFBD expression cassettes were developed to simultaneously degrade AFB and produce ethanol using AFB-contaminated rice as substrate. Thus, TV-AFBD has significant application potential in the AFB decomposition from contaminated agricultural products.