Effective degradation of aflatoxin B

Laccase has great potential for bioremediation, as it oxidizes both non-phenolic and phenolic substrates. In this work, we recombinantly produced the laccase enzyme from Heyndrickxia shackletonii using a combinative strategy of codon and induction optimization. The enzyme produced was purified. Afterward, the biochemical characteristics against the degradation of aflatoxin B1 (AFB1) and zearalenone (ZEN) were presented. The observed H. shackletonii Laccase-gene size was 1533 bp, and the purified enzyme’s molecular weight was estimated to be 56.7 kDa. The enzyme’s degradation potential against AFB1 and ZEN was 95.84% and 97.51%, respectively, after 24 h. The optimum pH for both AFB1 and ZEN was 8. Besides, the optimal temperatures were 40 °C and 55 °C for AFB1 and ZEN, respectively. Notably, the enzyme degraded AFB1 and ZEN simultaneously within 24 h, achieving degradation rates of 97.51% and 96.97%, respectively. Moreover, the study analyzed the storage stability of the enzyme; the HeshLac enzyme remained stable for 60 days at -20 °C and 4 °C, suggesting these are preferred storage conditions. The study also assessed the toxicity of the mycotoxins in zebrafish larvae, where noticeable developmental malformations were observed at the following concentrations: 0.1 µg/mL - AFB1 and 2 µg/mL - ZEN. Nonetheless, no or little changes were observed in the control. This study contributes to the knowledge of mycotoxin bioremediation, and the results are promising for decontaminating AFB1 and ZEN in the food or feed industry.