Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education P. R. C., Huhhot 010018, P. R. China; Key Laboratory of Dairy Products Processing, Ministry of Agriculture P. R. C., Inner Mongolia Agricultural University, Huhhot 010018, P. R. China.
Key Laboratory of Dairy Biotechnology and Engineering, Ministry of Education P. R. C., Huhhot 010018, P. R. China.
J Dairy Sci. 2017 Dec;100(12):9495-9507. doi: 10.3168/jds.2017-12970. Epub 2017 Sep 28.
Our study assayed angiotensin-converting enzyme (ACE) inhibitory activity and fermentation characteristics of 41 food-originated Lactobacillus casei strains in fermented milk production. Twenty-two of the tested strains produced fermented milks with a high ACE inhibitory activity of over 60%. Two strains (IMAU10408 and IMAU20411) expressing the highest ACE inhibitory activity were selected for further characterization. The heat stability (pasteurization at 63°C for 30 min, 75°C for 25 s, and 85°C for 20 s) and resistance to gastrointestinal proteases (pepsin, trypsinase, and sequential pepsin/trypsinase treatments) of the ACE inhibitory activity in the fermented milks produced with IMAU10408 and IMAU20411 were determined. Interestingly, such activity increased significantly after the heat or protease treatment. Because of the shorter milk coagulation time of L. casei IMAU20411 (vs. IMAU10408), it was selected for optimization experiments for ACE inhibitory activity production. Our results show that fermentation temperature of 37°C, inoculum density of 1 × 10 cfu/g, and fermentation time of 12 h were optimal for maximizing ACE inhibitory activity. Finally, the metabolite profiles of L. casei IMAU20411 after 2 and 42 h of milk fermentation were analyzed by ultra-HPLC electron spray ionization coupled with time-of-flight mass spectrometry. Nine differential abundant metabolites were identified, and 2 of them showed a strong and positive correlation with fermented milk ACE inhibitory activity. To conclude, we have identified a novel ACE inhibitory L. casei strain, which has potential for use as a probiotic in fermented milk production.
我们的研究测定了 41 株食品来源的干酪乳杆菌在发酵乳生产中的血管紧张素转换酶（ACE）抑制活性和发酵特性。在测试的 22 株菌株中，有 22 株菌株生产的发酵乳具有超过 60%的高 ACE 抑制活性。选择表达最高 ACE 抑制活性的两株菌株（IMAU10408 和 IMAU20411）进行进一步表征。测定了 IMAU10408 和 IMAU20411 生产的发酵乳中 ACE 抑制活性的热稳定性（63°C 巴氏杀菌 30 分钟、75°C 25 秒和 85°C 20 秒）和对胃肠道蛋白酶（胃蛋白酶、胰蛋白酶和顺序胃蛋白酶/胰蛋白酶处理）的抗性。有趣的是，这种活性在热或蛋白酶处理后显著增加。由于干酪乳杆菌 IMAU20411 的牛奶凝固时间更短（与 IMAU10408 相比），因此选择其进行 ACE 抑制活性生产的优化实验。结果表明，发酵温度为 37°C、接种密度为 1×10 cfu/g、发酵时间为 12 h 是最大限度提高 ACE 抑制活性的最佳条件。最后，通过超高效液相色谱-电喷雾电离-飞行时间质谱分析了干酪乳杆菌 IMAU20411 在牛奶发酵 2 和 42 小时后的代谢物谱。鉴定出 9 种差异丰度代谢物，其中 2 种与发酵乳 ACE 抑制活性呈强正相关。总之，我们已经鉴定出一种新型的 ACE 抑制干酪乳杆菌菌株，它有可能作为益生菌用于发酵乳生产。
