A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B1

Zhou, Zhimin; Li, Renkuan; Ng, Tzi Bun; Lai, Yunyun; Yang, Jie; Ye, Xiuyun

doi:10.3390/toxins12080476

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A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B₁

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College of Chemical Engineering, Fuzhou University, Fuzhou 350116, China

The Key Laboratory of Marine Enzyme Engineering of Fujian Province, Fuzhou University, Fuzhou 350116, China

National Engineering Laboratory for High-efficient Enzyme Expression, Fuzhou 350116, China

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School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong 999077, China

Author to whom correspondence should be addressed.

Toxins 2020, 12(8), 476; https://doi.org/10.3390/toxins12080476

Received: 22 June 2020 / Revised: 22 July 2020 / Accepted: 24 July 2020 / Published: 27 July 2020

(This article belongs to the Section Mycotoxins)

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Abstract

Aflatoxin B₁ (AFB₁) is a known toxic human carcinogen and can be detoxified by laccases, which are multicopper oxidases that convert several environmental pollutants and toxins. In this study, a new laccase that could catalyze AFB₁ degradation was purified and identified from the white-rot fungus Cerrena unicolor 6884. The laccase was purified using (NH₄)₂SO₄ precipitation and anion exchange chromatography, and then identified as Lac 2 through zymogram and UHPLC-MS/MS based on the Illumina transcriptome analysis of C. unicolor 6884. Six putative laccase protein sequences were obtained via functional annotation. The lac 2 cDNA encoding a full-length protein of 512 amino acids was cloned and sequenced to expand the fungus laccase gene library for AFB₁ detoxification. AFB₁ degradation by Lac 2 was conducted in vitro at pH 7.0 and 45 °C for 24 h. The half-life of AFB₁ degradation catalyzed by Lac 2 was 5.16 h. Acetosyringone (AS), Syrinagaldehyde (SA) and [2,2′ -azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid)] (ABTS) at 1 mM concentration seemed to be similar mediators for strongly enhancing AFB₁ degradation by Lac 2. The product of AFB₁ degradation catalyzed by Lac 2 was traced and identified to be Aflatoxin Q₁ (AFQ₁) based on mass spectrometry data. These findings are promising for a possible application of Lac 2 as a new aflatoxin oxidase in degrading AFB₁ present in food and feeds. View Full-Text

Keywords: laccase; Cerrena unicolor; aflatoxin B₁; biodegradation; detoxification; product; transcriptome

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MDPI and ACS Style

Zhou, Z.; Li, R.; Ng, T.B.; Lai, Y.; Yang, J.; Ye, X. A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B₁. Toxins 2020, 12, 476. https://doi.org/10.3390/toxins12080476

AMA Style

Zhou Z, Li R, Ng TB, Lai Y, Yang J, Ye X. A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B₁. Toxins. 2020; 12(8):476. https://doi.org/10.3390/toxins12080476

Chicago/Turabian Style

Zhou, Zhimin, Renkuan Li, Tzi B. Ng, Yunyun Lai, Jie Yang, and Xiuyun Ye. 2020. "A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B₁" Toxins 12, no. 8: 476. https://doi.org/10.3390/toxins12080476

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A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B₁

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