Xu Jie, Fang Fang
Key Laboratory of Industrial Biotechnology, Ministry of Education, Jiangnan University, Wuxi 214122, Jiangsu, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, Jiangsu, China.
Sheng Wu Gong Cheng Xue Bao. 2019 Jul 25;35(7):1286-1294. doi: 10.13345/j.cjb.180531.
Biogenic amines (BAs) are low molecular weight organic compounds that present in fermented foods. Large amount of ingested biogenic amines can cause allergy or significant symptoms. Reduction of BAs by enzymatic reaction in fermented foods is one of the most efficient methods for removal of biohazard compounds and assurance food safety. In this study, the multicopper oxidase (MCO) gene in the genome of Lactobacillus fermentum was successfully cloned in Escherichia coli BL21 and expressed at 484 U/L. The recombinant MCO was purified by the immobilized metal affinity chromatography method. The optimal reaction temperature and pH for this enzyme was detected to be 50 °C and 3.5. The Km and Vmax values of the recombinant MCO was determined to be 1.30 mmol/L and 7.67×10⁻² mmol/(L·min). Moreover, this MCO dramatically degrades histamine and tyramine by 51.6% and 40.9%, and can degrade other BAs including tryptamine, phenylethylamine, putrescine, cadaverine and spermidine, and was found to be tolerant to 18% (W/V) NaCl. The recombinant MCO is also capable of degrading BAs in soy sauce. The degradation rate of total BAs in soy sauce reaches 10.6% though a relatively low level of enzyme (500 U/L) is used. Multicopper oxidase has the potential to degrade biogenic amines in fermented foods, which lays a foundation for the further application of this kind of food enzymes.
生物胺（BAs）是存在于发酵食品中的低分子量有机化合物。大量摄入生物胺会引发过敏或出现明显症状。通过发酵食品中的酶促反应来降低生物胺含量，是去除生物危害化合物和确保食品安全的最有效方法之一。在本研究中，发酵乳杆菌基因组中的多铜氧化酶（MCO）基因在大肠杆菌BL21中成功克隆并以484 U/L的水平表达。重组MCO通过固定化金属亲和层析法进行纯化。检测到该酶的最佳反应温度和pH分别为50℃和3.5。重组MCO的Km和Vmax值分别确定为1.30 mmol/L和7.67×10⁻² mmol/(L·min)。此外，这种MCO能使组胺和酪胺显著降解51.6%和40.9%，并且能降解包括色胺、苯乙胺、腐胺、尸胺和亚精胺在内的其他生物胺，还发现其能耐受18%（W/V）的NaCl。重组MCO也能够降解酱油中的生物胺。尽管使用的酶水平相对较低（500 U/L），但酱油中总生物胺的降解率达到了10.6%。多铜氧化酶具有降解发酵食品中生物胺的潜力，这为这类食品酶的进一步应用奠定了基础。
