干酪乳杆菌21008体外降胆固醇活性研究

Study on the cholesterol-reducing activity of Lactobacillus casei 21008 in vitro

用胆固醇氧化酶指示平板和测定胆固醇氧化酶活力的方法对干酪乳杆菌21008是否具有产生胆固醇氧化酶的能力进行了研究,并以添加胆固醇的MRS培养基和蛋黄对菌株降胆固醇能力进行了评价。结果发现干酪乳杆菌能产生胆固醇氧化酶类似物,并且测得胞内酶活为302.7U/L,但没有胞外酶。菌株使MRS-CHO培养基中的胆固醇降低69.5%,主要是通过菌体细胞吸收、转化作用;而在蛋黄中发酵,优化条件下:V蛋黄∶V水=2∶1,接种量8%,发酵30h,胆固醇降低16.82%,pH降为5.57。

Lactobacillus casei 21008 was studied for its ability of producing cholesterol oxidase through cholesterol oxidase indicator plates and by measuring cholesterol oxidase activity. And the ability of its cholesterol-reducting activity in vitro was assessed in MRS-CHO medium and liquid egg yolk. Results indicated that L. casei 21008 was negative for extracellular synthesis of cholesterol oxidase,while observed intracellular cholesterol oxidase-like enzyme,and L. casei 21008 showed 302.7U/L enzyme activity. The reduction of the cholesterol level reached 69.5% in MRS-CHO broth after 18h,which mainly depended on the adsorption and assimilation. Orthogonal experiments in liquid egg yolk estimated that the optimum condition of the factors for cholesterol removal by L. casei 21008 was egg yolk∶water=2∶1（v/v）,8%（v/v） inoculum,30h fermentation. Validation experiments showed that the cholesterol reduction rate was 16.82%,pH5.57.