Enzymatic Oxidation of Aflatoxin M<sub>1</sub> in Milk Using CotA Laccase
Aflatoxin M<sub>1</sub> (AFM<sub>1</sub>) in milk poses a significant threat to human health. This study examined the capacity of <i>Bacillus licheniformis</i> CotA laccase to oxidize AFM<sub>1</sub>. The optimal conditions for the CotA laccase-catalyz...
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| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-11-01
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| Series: | Foods |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2304-8158/13/22/3702 |
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| Summary: | Aflatoxin M<sub>1</sub> (AFM<sub>1</sub>) in milk poses a significant threat to human health. This study examined the capacity of <i>Bacillus licheniformis</i> CotA laccase to oxidize AFM<sub>1</sub>. The optimal conditions for the CotA laccase-catalyzed AFM<sub>1</sub> oxidation were observed at pH 8.0 and 70 °C, achieving an AFM<sub>1</sub> oxidation rate of 86% in 30 min. The <i>K</i>m and Vmax values for CotA laccase with respect to AFM<sub>1</sub> were 18.91 μg mL<sup>−1</sup> and 9.968 μg min<sup>−1</sup> mg<sup>−1</sup>, respectively. Computational analysis suggested that AFM<sub>1</sub> interacted with CotA laccase via hydrogen bonding and van der Waals interactions. Moreover, the oxidation products of AFM<sub>1</sub> mediated by CotA laccase were identified as the C3-hydroxy derivatives of AFM<sub>1</sub> by HPLC-FLD and UPLC-TOF/MS. Toxicological assessment revealed that the hepatotoxicity of AFM<sub>1</sub> was substantially reduced following oxidation by CotA laccase. The efficacy of CotA laccase in removing AFM<sub>1</sub> in milk was further tested, and the result showed that the enzyme agent achieved an AFM<sub>1</sub> removal rate of 83.5% in skim milk and 65.1% in whole milk. These findings suggested that CotA laccase was a novel AFM<sub>1</sub> oxidase capable of eliminating AFM<sub>1</sub> in milk. More effort is still needed to improve the AFM<sub>1</sub> oxidase activity of CotA laccase in order to shorten the processing time when applying the enzyme in the milk industry. |
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| ISSN: | 2304-8158 |