1. A New Laccase of Lac 2 from the White Rot Fungus Cerrena unicolor 6884 and Lac 2-Mediated Degradation of Aflatoxin B 1 .
- Author
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Zhou Z, Li R, Ng TB, Lai Y, Yang J, and Ye X
- Subjects
- Amino Acid Sequence, Food Contamination prevention & control, Laccase genetics, Laccase isolation & purification, Phylogeny, Polyporales genetics, Aflatoxin B1 chemistry, Laccase chemistry, Polyporales enzymology
- Abstract
Aflatoxin B
1 (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 )2 SO4 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.- Published
- 2020
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