降胆固醇乳酸杆菌的筛选及对小鼠血清胆固醇的影响

目的：从羊新鲜粪便中分离筛选具有降胆固醇能力的乳酸杆菌，探讨其对小鼠血清胆固醇含量的影响。方法：以碳酸钙-MRS培养基和胆固醇-MRS培养基筛选具有高效降胆固醇能力的乳酸杆菌；利用形态特征、生理生化特性和16S rDNA序列分析鉴定分离菌株L-3。为了验证其效果，将40 只8 周龄雄性BALB/c小鼠随机分为基础饲料组（A）、高脂模型组（B）、高脂模型＋生理盐水组（C）、高脂模型＋菌株L-3组（D）。分别饲喂第15、30天，采血，测定总胆固醇（total cholesterol，TC）、总甘油三酯（triglyceride，TG）和高密度脂蛋白胆固醇（highdensity lipoprotein-cholesterol，HDL-C）的含量。结果：筛选得到一株能够高效降解胆固醇的菌株L-3，胆固醇降解率达到（35.93±0.43）%，经鉴定为植物乳杆菌。饲喂第15天，成功构建出高脂血症小鼠模型。灌胃第30天，与B组相比，D组TC、TG、动脉硬化指数水平均极显著降低（P＜0.01），HDL-C水平显著升高（P＜0.05），HDL-C/TC水平极显著升高（P＜0.01），而对照组几乎无降胆固醇效果（P＞0.05）。结论：实验获得了1 株在体内外均具有高效降胆固醇能力的植物乳杆菌Lactobacillus plantarum L-3，为进一步开发其为功能性微生态制剂提供了可能。

Screening of Lactobacillus with Cholesterol-Degrading Property and Its Effect on Serum Cholesterol in Mice

Objective: To screen Lactobacillus with high cholesterol-degrading capacity from fresh sheep feces and
explore the effect of the screened strain on serum cholesterol level in hypercholesterolemic mice. Methods: We screened
Lactobacillus with high cholesterol-reducing capacity using Calcium Carbonate-Man-Rogosa-Sharp (MRS) medium
and cholesterol-MRS medium. The screened strain, named as L-3, was identified by colony morphology, physiological
and biochemical tests and 16S rDNA sequencing. A feeding experiment was conducted on forty Kunming male mice
(eight weeks old). The mice were randomly divided 4 groups: A, B, C and D, which were fed with normal diet, high
fat diet (HFD), HFD plus normal saline and HFD plus strain L-3, respectively. The serum levels of total cholesterol
(TC), triglyceride (TG), and high density lipoprotein-cholesterol (HDL-C) were determined on the 15th and 30th day of
the experiment. Results: This selected strain was identified as Lactobacillus plantarum L-3 and the degradation rate
of cholesterol by the stain could reach up to (35.93 ± 0.43)%. A hypercholesterolemic mice model was successfully
constructed after feeding a high-cholesterol diet for 15 days. Compared with group B, serum TC, TG and AI levels
were extremely significantly decreased in group D after 30 days of oral administration of strain L-3 (P < 0.01), HDL-C
levels of group D was significantly increased (P < 0.05), and HDL-C/TC levels were extremely significantly increased
(P < 0.01). However, the negative control group did not show cholesterol degradation (P > 0.05). Conclusion: L. plantarum
L-3 has probiotic potential as indicated by its hypocholesterolemic effect both in vivo and in vitro.