产ACE抑制肽菌株的筛选及其在模拟消化道环境中的活性分析

为了筛选出对血管紧张素转换酶（angiotensin-converting enzyme，ACE）抑制活性较高并且具有较强的耐酸耐胆盐和耐盐的乳酸菌，对实验室保存的27株乳酸菌进行了产酸能力、蛋白水解活力、ACE抑制活性、模拟胃肠道消化及酸、胆盐和盐耐受性的测定。结果显示，菌株M3的ACE抑制率可达71.94%±1.39%，具有较好的蛋白水解活力和产酸能力，蛋白水解活力为（86.66±3.51）μg/mL亮氨酸，滴定酸度为（71.67±2.86）°T。菌株M3经人工胃肠液分别处理3 h后，ACE抑制率为74.96%±1.73%；在pH3的环境中3 h，耐受性为14.34%±1.21%，活菌数能达到7 lg CFU mL?1以上；在含有0.3%胆盐的培养基中3 h，耐受性为37.50%±2.47%；在含有4% NaCl的培养基中24 h，耐受性为37.32%±1.84%。该菌经16S rDNA鉴定为Lactobacillus (Lb.) paracasei subsp. paracasei M3。因此，菌株Lb. paracasei subsp. paracasei M3可用作发酵牛乳富产ACE抑制肽且能耐受消化道环境具有益生菌潜力的菌株。

Screening of ACE-inhibiting Peptide Producing Strains and Their Activity Analysis in Simulated Digestive Tract Environment

The acid production capacity, protein hydrolysis activity, ACE inhibition activity, simulated gastrointestinal digestion and acid, bile salt and salt tolerance of 27 strains of lactic acid bacteria kept in the laboratory were determined in order to screen for those with high angiotensin-converting enzyme (ACE) inhibition activity and high acid, bile salt and salt tolerance. The results showed that the ACE inhibition rate of strain M3 could reach 71.94%±1.39%, with good protein hydrolysis activity and acid production ability, the protein hydrolysis activity was (86.66±3.51) μg/mL leucine, and the titration acidity was (71.67±2.86) °T. The ACE inhibition rate of strain M3 was 74.96%±1.73% after 3 h of treatment with artificial gastrointestinal fluid, respectively. It was treated for 3 h in pH3 broth medium and the survival rate was 14.34%±1.21% and the viable count could reach more than 7 lg CFU mL?1. It was treated for 3 h in broth medium containing 0.3% bile salts and the survival rate was 37.50%±2.47%. It was treated for 24 h in broth medium containing 4% NaCl and the survival rate was 37.32%±1.84%. The bacterium was identified by 16S rDNA as Lactobacillus (Lb.) paracasei subsp. paracasei M3. Thus, Lb. paracasei subsp. paracasei M3 can be used as an ACE-inhibiting peptide-rich strain for fermenting cow’s milk and tolerating the digestive environment with probiotic potential.