泡菜源乳酸菌的分离筛选及其对小鼠氧化应激水平的改善作用

为筛选具有较好体外抗性以及体内抗氧化效果的乳酸菌，本研究从重庆农家自然发酵泡菜中分离得到12株菌株，经16S rDNA种属分析表明，其中植物乳杆菌（Lactobacillus plantarum） 4株，发酵乳杆菌（Lactobacillus fermentum） 7株，短乳杆菌（Lactobacillus brevis） 1株。采用pH 3.0人工胃液和0.3%胆盐对乳酸菌进行体外抗性筛选，发现12株乳酸杆菌具有较好的体外抗性，其中10株乳酸杆菌在pH 3.0人工胃液中处理3 h后的存活率超过80%；2株乳酸杆菌在0.3%胆盐中的存活率超过60%。选取体外抗性好且为食品可用菌种的Lactobacillus fermentum CQPC-11（L. fermentum CQPC-11）为实验菌株，评价其对活性炭冰水诱导氧化应激损伤小鼠的改善作用，结果表明H-LF CQPC11组小鼠血清中总超氧化物歧化酶（T-SOD）、谷胱甘肽过氧化物酶（GSH-Px）和过氧化氢酶（CAT）的酶活力分别为67.73 U/mL、2742.35酶活力单位、136.59 U/mL，显著高于模型组（p<0.05），而丙二醛（MDA）的含量为1.99 nmol/L，显著低于模型组（p<0.05）。综上所述，L. fermentum CQPC-11不仅具备良好的耐胃酸和耐胆盐能力，还能降低氧化应激模型小鼠的氧化应激反应，可通过后续进一步的实验探讨该菌株抗氧化作用的具体机理，为新型微生态制剂以及功能性乳酸菌食品的开发提供理论依据和可用菌株。

Isolation and Screening of Lactic Acid Bacteria from Pickle and its Improvement Effect on Oxidative Stress Level in Mice

In order to screen lactic acid bacteria with good in vitro resistance and antioxidative effect in vivo, 12 strains were isolated from natural fermented pickle in Chongqing farmhouse. 16S rDNA species analysis showed that 4 strains are Lactobacillus plantarum, 7 strains are Lactobacillus fermentum, and 1 strain is Lactobacillus brevis. The in vitro resistance of lactic acid bacteria were tested using artificial gastric juice (pH 3.0) and 0.3% of bile salt, it was found that all 12 strains of Lactobacillus had good resistance in vitro. The survival rate of 10 strains of Lactobacillus in artificial gastric juice at pH 3.0 for 3 h exceeded 80%; the survival rate of 2 strains of Lactobacillus in 0.3% bile salt exceeded 60%. L. fermentum CQPC-11, which has good resistance in vitro and is a usable strain of food, was selected as the experimental strain, and its improvement effect on activated carbon ice water-induced oxidative damage in mice was evaluated. The results showed that the enzyme activities of T-SOD, GSH-Px and CAT in the serum of mice in the H-LF CQPC11 group were 67.73±5.42 U/mL, 2742.35±107.35 enzyme activity units, and 136.59±18.72 U/mL, respectively, which were significantly higher than the model group (p<0.05), and the content of MDA was 1.99±0.14 nmol/L, which was significantly lower than the model group (p<0.05). In summary, L. fermentum CQPC-11 not only has good resistance to gastric acid and bile salts, but also reduces oxidative stress response in oxidative stress model mice. The specific mechanism of the anti-oxidant effect of this strain can be explored through subsequent experiments, so as to provide a theoretical basis and available strains for the development of new micro-ecological preparations and functional lactic acid bacteria food.