Simultaneous degradation of two mycotoxins enabled by a fusion enzyme in food-grade recombinant Kluyveromyces lactis

Aflatoxin B-1 (AFB(1)) and zearalenone (ZEN) are two predominant mycotoxins ubiquitously found in corn, peanuts, and other grains, which pose a great threat to human health. Therefore, safe and effective methods for detoxification of these mycotoxins are urgently needed. To achieve simultaneous degradation of multiple mycotoxins, a fusion enzyme ZPF1 was constructed by linking zearalenone hydrolase and manganese peroxidase with a linker peptide GGGGS. This fusion enzyme was secretory expressed successfully in the newly constructed food-grade recombinant strain Kluyveromyces lactis GG799(pKLAC1-ZPF1), and was investigated with the mycotoxins degradation efficiency in two reaction systems. Results showed that both AFB(1) and ZEN can be degraded by ZPF1 in reaction system 1 (70.0 mmol/L malonic buffer with 1.0 mmol/L MnSO4, 0.1 mmol/L H2O2, 5.0 mu g/mL AFB(1) and ZEN, respectively) with the ratios of 46.46% and 38.76%, respectively. In reaction system 2 (50.0 mmol/L Tris-HCl, with 5.0 mu g/mL AFB(1) and ZEN, respectively), AFB(1) cannot be degraded while ZEN can be degraded with the ratio of 35.38%. To improve the degradation efficiency of these mycotoxins, optimization of the induction and degradation conditions were fulfilled subsequently. The degradation ratios of AFB(1) and ZEN by ZPF1 in reaction system 1 reached 64.11% +/- 2.93% and 46.21% +/- 3.17%, respectively. While in reaction system 2, ZEN was degraded by ZPF1 at a ratio of 41.45% +/- 3.34%. The increases of degradation ratios for AFB(1) and ZEN in reaction system 1 were 17.65% and 7.45%, respectively, while that for ZEN in reaction system 2 was 6.07%, compared with the unoptimized results.

Automated summary

A fusion enzyme ZPF1 was constructed for simultaneous degradation of Aflatoxin B-1 and zearalenone, showing improved degradation efficiency after optimization.