Bacillus haynesii来源的重组BH CotA漆酶对黄曲霉毒素B1和玉米赤霉烯酮的降解性能研究

    Research on the degradation performance of recombinant BH CotA laccase from Bacillus haynesii towards aflatoxin B1 and zearalenone

    • 摘要: 粮食及饲料体系中黄曲霉毒素B1(AFB1)和玉米赤霉烯酮(zearalenone, ZEN)污染普遍,且难以通过传统物理化学手段彻底去除,亟需开发高效、安全的降解策略。通过BlastP比对挖掘真菌毒素降解酶,并对其酶学特性进行测定,同时采用分子对接分析蛋白-小分子相互作用,利用超高效液相色谱-串联质谱对降解产物进行分析,并通过斑马鱼模型评价产物毒性。结果表明:从Bacillus haynesii中成功鉴定出一种名为BH CotA的漆酶,其分子质量为59.4 kDa;在pH 8、70 ℃条件下,BH CotA对AFB1和ZEN均表现出良好的降解效果;在30~70 ℃和pH 8~10范围内孵育1 h后,BH CotA仍能保持90%以上的相对活性,展现出优异的热稳定性和pH稳定性;BH CotA将AFB1氧化为AFQ1,将ZEN氧化为15-OH-ZEN,经斑马鱼肝毒性试验验证,其毒性显著低于AFB1和ZEN。研究结果为食品和饲料中AFB1和ZEN的生物解毒提供了重要参考。

       

      Abstract: Aflatoxin B1 (AFB1) and zearalenone (ZEN) are prevalent fungal contaminants in grains and feed, posing significant risks to human and animal health. In recent years, enzyme-based biodegradation has emerged as a safe and efficient strategy for mitigating mycotoxin contamination. This study utilized BlastP analysis to identify candidate mycotoxin-degrading enzymes, which were subsequently characterized for their enzymatic properties. Molecular docking was performed to analyze interactions between the enzyme and its substrates, while UHPLC-MS/MS was employed to identify degradation products. Additionally, the toxicity of these degradation products was assessed using a zebrafish liver toxicity model. The findings revealed that a novel CotA laccase, designated as BH CotA, was successfully identified from Bacillus haynesii, with a molecular mass of 59.4 kDa. BH CotA demonstrated robust degradation activity toward both AFB1 and ZEN under conditions of pH 8.0 and 70 ℃. The enzyme retained over 90% of its initial activity after 1 h of incubation across a temperature range of 30-70 ℃ and a pH range of 8.0-10.0, highlighting its excellent thermal and pH stability. UHPLC-MS/MS analysis confirmed that BH CotA oxidized AFB1 into AFQ1 and converted ZEN into 15-OH-ZEN. Zebrafish liver toxicity assays further demonstrated that both AFQ1 and 15-OH-ZEN exhibited significantly reduced toxicity compared with their parent compounds. Collectively, this study introduces a promising enzymatic bioremediation approach for the effective detoxification of AFB1 and ZEN in food and feed systems, laying a foundation for the development of safe and practical mycotoxin control strategies.

       

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