Journal article Open Access

Aflatoxin B1 andM1 Degradation by Lac2 from Pleurotus pulmonarius and Redox Mediators

Martina Loi, Francesca Fanelli, Paolo Zucca, Vania Liuzzi, Laura Quintieri, Maria Cimmarusti, Linda Monaci, Miriam Haidukowski, Antonio Logrieco, Enrico Sanjust, Giuseppina Mulè

Laccases (LCs) are multicopper oxidases that find application as versatile biocatalysts
for the green bioremediation of environmental pollutants and xenobiotics. In this study we
elucidate the degrading activity of Lac2 pure enzyme form Pleurotus pulmonarius towards aflatoxin
B1 (AFB1) and M1 (AFM1). LC enzyme was purified using three chromatographic steps and
identified as Lac2 through zymogram and LC-MS/MS. The degradation assays were performed
in vitro at 25 C for 72 h in buffer solution. AFB1 degradation by Lac2 direct oxidation
was 23%. Toxin degradation was also investigated in the presence of three redox mediators,
(2,20-azino-bis-[3-ethylbenzothiazoline-6-sulfonic acid]) (ABTS) and two naturally-occurring phenols,
acetosyringone (AS) and syringaldehyde (SA). The direct effect of the enzyme and the mediated
action of Lac2 with redox mediators univocally proved the correlation between Lac2 activity and
aflatoxins degradation. The degradation of AFB1 was enhanced by the addition of all mediators at
10 mM, with AS being the most effective (90% of degradation). AFM1 was completely degraded by
Lac2 with all mediators at 10 mM. The novelty of this study relies on the identification of a pure
enzyme as capable of degrading AFB1 and, for the first time, AFM1, and on the evidence that the
mechanism of an effective degradation occurs via the mediation of natural phenolic compounds.
These results opened new perspective for Lac2 application in the food and feed supply chains as a
biotransforming agent of AFB1 and AFM1.

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