摘要
对已经分离和筛选得到的胆固醇吸收同化率高的乳酸菌,初步探究其体外降胆固醇的机制,以期为具有降胆固醇活性的功能性发酵食品的研发提供理论基础。通过初筛得到具有降胆固醇活性的菌株,再以皂化-比色法进行复筛,从而获得胆固醇吸收同化效率高的乳酸菌。这些乳酸菌的胆固醇转化率介于(3.30±0.89)%～(75.64±1.12)%之间,平均转化率达44.34%。其中,有14株乳酸菌的胆固醇吸收同化能力强于平均水平。Lactobacillus plantarum S11的胆固醇吸收同化率高达(75.64±1.12)%,测定菌体破碎后洗脱上清及细胞碎片悬浮液中胆固醇含量显示,4.20×109cfu/mL的菌体仅能吸附沉淀0.002 mg的胆固醇(仅占1.30%),可见,Lb. plantarum S11菌株主要通过吸收同化作用达到降胆固醇目的,吸附及掺入细胞膜作用仅是该菌株降胆固醇的次要途径。本研究所创建的分离筛选方法确实能应用于从传统发酵食品中筛选具有降胆固醇能力的益生菌菌株,并有助于后续新型降胆固醇乳酸菌发酵产品的研发。
The lactobacilli which has high cholesterol uptake and utilization rate are isolated after screening. Their cholesterol-reducing mechanism is detected in vitro,to provide a theoretical basis for cholesterol-reducing fermented food research and development. The probiotic strains with cholesterol-reducing activity are first obtained by screening. Then the saponification-colorimetric screening is performed to obtain lactobacillus strains with high cholesterol absorption efficiency. The lactobacilli has cholesterol-reducing rates ranged from(3.30 ±0.89)% ～(75.64 ±1.12)%,with the average rate of 44.34%. Among them,14 strains have higher cholesterol-reducing rate than average.Lb. plantarum S11 is the strain with the cholesterol-reducing rate as high as(75.64 ±1.12)%. It is indicated that only 0.002 mg of cholesterol is adsorbed and precipitated by 4.20 ×109 cfu/mL of Lb.plantarum S11 cells by determine the content of cholesterol in the suspension of the disrupted cells(only 1.30%). This results indicate that the cholesterol-reducing activity of Lb. plantarum S11 is achieved mainly by absorbing and assimilation,but not absorbing and incorporating in cell membrane.The screening and isolation methods in this study can be applied to select cholesterol-reducing probiotics from traditional fermented foods. And it is also helpful for follow-up development of new cholesterol-reducing lactobacilli fermented products.
引文
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