Institute of Grain & Oil Science and Technology, Academy of National Food and Strategic Reserves Administration, Beijing 100037, China.
Institute of Plant Protection, Chinese Academy of Agricultural Science, Beijing 100094, China.
Toxins (Basel). 2020 Feb 13;12(2):117. doi: 10.3390/toxins12020117.
The estrogen-like mycotoxin zearalenone (ZEN) is one of the most widely distributed contaminants especially in maize and its commodities, such as corn oil. ZEN degrading enzymes possess the potential for counteracting the negative effect of ZEN and its associated high safety risk in corn oil. Herein, we targeted enhancing the secretion of ZEN degrading enzyme by Pichia pastoris through constructing an expression plasmid containing three optimized expression cassettes of zlhy-6 codon and signal peptides. Further, we explored various parameters of enzymatic detoxification in neutralized oil and analyzed tocopherols and sterols losses in the corn oil. In addition, the distribution of degraded products was demonstrated as well by Agilent 6510 Quadrupole Time-of-Flight mass spectrometry. P. pastoris GSZ with the glucoamylase signal was observed with the highest ZLHY-6 secretion yield of 0.39 mg/mL. During the refining of corn oil, ZEN in the crude oil was reduced from 1257.3 to 13 µg/kg (3.69% residual) after neutralization and enzymatic detoxification. Compared with the neutralized oil, no significant difference in the total tocopherols and sterols contents was detected after enzymatic detoxification. Finally, the degraded products were found to be entirely eliminated by washing. This study presents an enzymatic strategy for efficient and safe ZEN removal with relatively low nutrient loss, which provides an important basis for further application of enzymatic ZEN elimination in the industrial process of corn oil production.
类雌激素真菌毒素玉米赤霉烯酮（ZEN）是分布最广泛的污染物之一，尤其是在玉米及其制品如玉米油中。ZEN 降解酶具有中和 ZEN 及其相关高安全风险的潜力，可应用于玉米油。在此，我们通过构建包含三个优化的 zlhy-6 密码子和信号肽表达盒的表达质粒，靶向增强毕赤酵母中 ZEN 降解酶的分泌。此外，我们还在中性油中探索了酶解毒的各种参数，并分析了玉米油中生育酚和甾醇的损失。此外，还通过安捷伦 6510 四重四极杆飞行时间质谱证明了降解产物的分布。含有葡萄糖淀粉酶信号肽的毕赤酵母 GSZ 观察到 ZLHY-6 的分泌产量最高，为 0.39mg/mL。在玉米油精炼过程中，经过中和和酶解毒，粗油中的 ZEN 从 1257.3µg/kg 降低至 13µg/kg（残留 3.69%）。与中和油相比，酶解毒后总生育酚和甾醇含量没有显著差异。最后，发现降解产物通过洗涤完全消除。本研究提出了一种高效、安全的 ZEN 去除的酶法策略，具有相对较低的营养损失，为进一步将酶法 ZEN 消除应用于玉米油生产的工业过程提供了重要依据。
