Immobilization of recombinant Trametes versicolor aflatoxin B-degrading enzyme (TV-AFBD) with montmorillonite for absorption and in situ degradation of aflatoxin B.

Aflatoxin B is a highly carcinogenic and teratogenic substance mainly produced by toxin-producing strains such as Aspergillus flavus and Aspergillus parasitic. The efficient decomposition of aflatoxin is an important means to reduce its harm to humans and livestock. In this study, Trametes versicolor aflatoxin B-degrading enzyme (TV-AFBD) was recombinantly expressed in Bacillus subtilis (B. subtilis) 168. MMT-CTAB-AFBD complex was prepared by the immobilization of TV-AFBD and montmorillonite (MMT) by cross-linking glutaraldehyde. The results indicated that TV-AFBD could recombinantly express in engineered B. subtilis 168 with a size of approximately 77 kDa. The immobilization efficiency of MMT-CTAB-AFBD reached 98.63% when the concentration of glutaraldehyde was 5% (v/v). The relative activity of TV-AFBD decreased to 72.36% after reusing for 10 times. The content of AFB in MMT-CTAB-AFBD-AFB decreased to 1.1 µg/g from the initial 5.6 µg/g after incubation at 50 °C for 6 h. The amount of 80.4% AFB in the MMT-CTAB-AFBD-AFB complex was degraded by in situ catalytic degradation. Thus, the strategy of combining adsorption and in situ degradation could effectively reduce the content of AFB residue in the MMT-CTAB-AFBD complex.