米糠脂肪酶使米糠发生酸败，常规热处理方法难以完全灭活米糠内源脂肪酶。为评价米糠中耐热脂肪酶的存在，该研究以湿热稳定化处理的米糠为原料，考察表面活性剂类型及浓度对米糠粗酶液脂肪酶活性影响，进一步比较两种脂肪酶特性，曲拉通-磷酸盐米糠脂肪酶（TRBL）和磷酸盐米糠脂肪酶（PRBL）。采用10 mmol/L表面活性剂提取粗酶液脂肪酶活性显著升高，其中曲拉通组效果最优。对比TRBL和PRBL性质发现，PRBL最适反应温度和pH值分别为30 ℃和7.0；而TRBL最适反应温度超过100 ℃，且具有较好耐热性，其最适反应pH值为3.0和7.0；两种粗酶液脂肪酶水解不同碳链的底物无显著特异性；Ba2+和Zn2+都能激活粗酶液脂肪酶活性，但Ba2+对TRBL脂肪酶活性激活作用远高于PRBL组；K+和Fe3+分别对PRBL和TRBL脂肪酶活性具有最大抑制作用；相比于PRBL，TRBL具有更好的有机溶剂耐受性，且甲醇对TRBL脂肪酶活性具有激活作用。研究证明了稳定化米糠中存在能耐受温度和有机溶剂的脂肪酶，为深入挖掘新型米糠脂肪酶提供了理论依据。

Rice bran lipase can make rice bran go rancid, and conventional heat treatment methods are difficult to completely inactivate endogenous lipase in rice bran. In order to evaluate the presence of heat-resistant lipase in rice bran, the present study was carried out to investigate the effects of surfactant type and concentration on the lipase activity of rice bran’s crude enzyme solution using the rice bran stabilized by the wet heat treatment as the raw material, and further compare the characteristics of the two lipases, Triton x-100 rice bran lipase (TRBL) and phosphate rice bran lipase (PRBL). The lipase activity of the crude enzyme solution extracted with 10 mmol/L surfactant increased significantly, with the Triton x-100 group exhibiting the best effect. Comparison on the properties of TRBL and PRBL revealed that the optimal reaction temperature and pH of PRBL were 30 ℃ and 7.0, respectively, whilst the optimal reaction temperature of TRBL was over 100 ℃ and it had good heat resistance, with the optimal reaction pH of being 3.0 and 7.0; The two crude liquid lipases had no significant specificity in the hydrolysis of substrates with different carbon chains; Ba2+ and Zn2+ could activate the lipase activity of the crude liquid enzymes, but the activation effect of Ba2+ on the activity of TRBL was much higher than that of the PRBL group. K+ and Fe3+ had the greatest inhibitory effect on the lipase activities of PRBL and TRBL, respectively; TRBL had better tolerance to organic solvents than PRBL, and methanol had an activating effect on TRBL’s lipase activity. The study proved that there were lipases that could tolerate temperature and organic solvents in stabilized rice bran, which provides a theoretical basis for in-depth exploration of novel rice bran lipases.

广东省重点研发计划项目（2020B020225004）；广东省自然科学基金项目（2023A1515030242；2021A1515010888）；广东省农业科学院创新基金产业专项（202229）；广东特支计划项目（2019BT02N112）；广东省现代农业产业共性关键技术研发创新团队建设项目（2023KJ117）；广东省财政厅专项（粤财农〔2022〕167号）；广东省农业科学院科技创新战略专项基金（R2023PY-JX018）