降解胆固醇乳酸菌株的体外筛选及其酸乳发酵特性研究

In vitro Screening of Cholesterol-Lowering Lactic Acid Bacteria and Study of Their Properties in Yogurt Fermentation

为筛选降解胆固醇、发酵酸乳、定植胃肠道的乳酸菌优良菌株,通过邻苯二甲醛法测定菌株体外降胆固醇能力,感官评价和质构仪测定降解菌株发酵酸乳能力,菌株在酸溶液、胆盐溶液、人工模拟胃液、人工模拟胰液中存活率考察胃肠道耐受性,筛选获得优良菌株,基于16S r DNA序列鉴定优良菌株。结果表明,250株供试菌株中只有8株胆固醇的降解率在40%以上,其中降解率最高的菌株"青A16"达54.64%,其发酵酸乳的感官评分和大多数质构指标值也最高,在4种体外模拟胃肠道溶液中存活率均达到了40%以上,分子生物学鉴定为耐久肠球菌。菌株"青A16"可作为开发功能性酸乳候选发酵菌株。

This study screened for lactic acid bacteria strains capable of efficiently reducing cholesterol that could also be used for yogurt fermentation and colonization of the gastrointestinal tract. The cholesterol-lowering activity of strains were tested using o-phthalaldehyde. Yogurt fermentation was evaluated by sensory evaluation and texture analysis. Gastrointestinal tract tolerance was determined based on the survival rate of the strains in acid solution,bile salt solution,artificial simulated gastric juice and artificial simulated pancreatic juice.Candidate strains were identified based on 16 S rDNA sequence. Of 250 strains screened,eight lactic acid bacteria strains displayed cholesterol-degradation rates exceeding 40%. The strain with the highest cholesteroldegradation rate(QingA16,54.64%)also displayed the highest sensory evaluation score,the most yogurt fermentation texture indices,and a survival rate exceeding 40% survival rate in four simulated gastrointestinal solutions in vitro. Molecular identification revealed the strain to be Enterococcus durans. This strain is a candidate fermentation strain for functional yogurt.