Yanli Xie

Co-contamination of aflatoxin B1 (AFB1) and zearalenone (ZEN) poses a major food safety risk. In this study, the copper-containing nitrite reductase AfNiR was identified as a novel biocatalyst for AFB1 and ZEN degradation, achieving maximum efficiencies of 99.22% and 93.53%, respectively, under optimal conditions of 40 °C, pH 7.0–8.0, 20 μg/mL (0.48 μM) enzyme dosage, and 24 h incubation for 5 μg/mL (16.01 μM) AFB1, and 50 °C, pH 8.0, 20 μg/mL (0.48 μM) enzyme dosage, and 24 h incubation for 10 μg/mL (31.41 μM) ZEN. UPLC–MS/MS identified AFQ1 and 15-OH-ZEN as the main transformation products, both exhibiting substantially reduced toxicity indicators in zebrafish assays. Molecular docking, site-directed mutagenesis, and molecular dynamics simulations indicated that both toxins bind near the T2 copper center and that copper-coordinating residues are essential for catalysis. To improve stability, AfNiR was immobilized in Cu3(PO4)2 nanoflowers and SA/SDS microspheres, achieving efficient detoxification in vegetable oil without affecting oil quality.

Aflatoxin B1 is a potent Group I carcinogen that contaminates food and feed, necessitating efficient detoxification strategies. This study isolated a novel bacterial strain, Enterobacter sp. HNGD-822 from soil, which efficiently degrades AFB1. Genome analysis identified two novel multicopper oxidase (laccase) genes, EbMCO1 and EbMCO2. The recombinant enzymes were heterologously expressed, exhibiting optimal activity at 50 °C and pH 7.0, with strict Cu2+ dependence. Within 12 h, EbMCO1 degraded over 99% of AFB1, while EbMCO2 also showed high activity under the same conditions. Both enzymes primarily converted AFB1 into AFQ1 and epi-AFQ1, products that exhibited significantly reduced hepatotoxicity, developmental toxicity, and oxidative stress in transgenic zebrafish. Applied to artificially contaminated peanut meal matrices, EbMCO1 and EbMCO2 achieved degradation efficiencies of 89.35% and 82.66%, respectively, without altering nutritional quality. This work presents novel laccases with promising potential for the biocontrol of AFB1 in the feed and food industries.

Co-contamination of foods with multiple mycotoxins highlights the need for broad-spectrum detoxification enzymes. In this study, Klebsiella pneumoniae HNGD-HS06 was isolated from contaminated peanuts and degraded aflatoxin B1 (AFB1), zearalenone (ZEN), and alternariol (AOH) by 72.52%, 63.42%, and 76.17%, respectively. Genome-guided screening and heterologous expression identified two candidate proteins, HSFtsp and HSCueO. HSCueO shared only 28.08% sequence identity with CotA laccase, while HSFtsp has not previously been associated with mycotoxin degradation. HSFtsp degraded AFB1, ZEN, and AOH by up to 99.16%, 95.12%, and 94.72%, respectively, whereas HSCueO achieved 98.97%, 99.23%, and 99.74% degradation. Product analysis and zebrafish assays suggested that both enzymes transformed these toxins into less toxic products, while molecular docking supported potential enzyme–substrate interactions. Both enzymes retained detoxification activity in contaminated peanut, corn, and wheat flour, expanding enzyme resources for multimycotoxin control in foods.

Mycotoxin contamination poses a significant hazard to feed safety and animal health. Fungal laccases have shown promise in mycotoxin degradation; however, their practical application remains limited due to insufficient catalytic efficiency and thermostability. In this study, a laccase (AsLac) from Aspergillus terreus HNGD-TM15 demonstrated potential for degrading aflatoxin B₁ (AFB₁) and zearalenone (ZEN). To enhance its performance, protein fusion technology was employed to construct a fusion enzyme, S1v1-AsLac. Compared to AsLac, S1v1-AsLac exhibited a 49% improvement in AFB₁ degradation and an 81% enhancement in ZEN degradation, along with a 2.02-fold extension in half-life at 60 °C, and improved storage stability. S1v1-AsLac effectively reduced AFB₁ and ZEN levels in contaminated feed samples, achieving degradation rates of 66.05% and 79.60% for corn flour and 62.61% and 69.43% for corn bran, respectively. These results present a promising approach for enhancing laccase performance and highlight potential for the degradation of mycotoxins in contaminated feed.

Mycotoxins are toxic secondary metabolites commonly found in cereal crops, posing significant health risks to humans and animals. In this study, a multicopper oxidase from Bacillus megaterium (BmCueO) has been identified as an effective catalyst for degrading Aflatoxin B₁ (AFB₁) and Zearalenone (ZEN). Through semi-rational design, a triple-point mutant (D373P/Q144Y/Q350F) was constructed to enhance its thermostability and catalytic performance. The engineered variant exhibited a 3.96-fold increase in half-life at 60 °C, along with improvements of 22.6% and 48.2% in AFB₁ and ZEN degradation activities, respectively. LC-MS/MS analysis confirmed the structural transformation of AFB₁ and ZEN into less toxic derivatives, while zebrafish and Ames assays verified reduced the toxicity and mutagenicity of the degradation products. The variant efficiently degraded AFB₁ and ZEN in feed matrices, demonstrating its potential for application. These results highlight the promise of the engineered BmCueO as a safe and efficient biocatalyst for mycotoxin detoxification in feed systems.

Alicyclobacillus acidoterrestris is a type of contaminating bacteria that can cause the spoilage of juice. To develop a nonthermal control method, lysozyme-modified copper phosphate nanoflowers (Ly@Cu₃(PO₄)₂ NFs) were fabricated. The microstructure and composition of the hybrids were characterized, and the antibacterial performance was further evaluated. Antibacterial results exhibited that Ly@Cu₃(PO₄)₂ NFs possessed effective performance against A. acidoterrestris with a minimum inhibitory concentration (MIC) of 4.0 μg mL^-1 and a minimum bactericidal concentration (MBC) of 64 μg mL^-1, respectively. Besides, Ly@Cu₃(PO₄)₂ NFs destroyed bacterial integrity and caused the leakage of a key intracellular substance. In vitro hemolysis test and in vivo zebrafish toxicity evaluation suggested the hybrids possessed satisfactory biocompatibility. Additionally, the antibacterial performance of Ly@Cu₃(PO₄)₂ NFs in apple juice was investigated, and the impact on juice quality was further evaluated. The aim of this work is to develop a novel nonthermal control method for Alicyclobacillus spp. contamination in the juice industry.