降胆固醇乳杆菌的综合评价及胆盐水解酶活性研究
发布时间：2018-12-06 09:49
【摘要】： 过量摄入胆固醇引起的心血管疾病严重危害人体健康,如何控制血清胆固醇水平受到越来越广泛的关注。乳杆菌降胆固醇作用虽已被大量报道,但其优良菌株的评价标准、明确的去除机理等方面仍不确定。 本研究首先建立了一套体外评价乳杆菌降胆固醇综合性能的标准。它包括菌株对模拟胃部pH值的耐受性,对模拟小肠胆汁浓度的耐受能力,降胆固醇性能——包括共沉淀作用和同化作用的分别评价,以及胆盐水解酶(Bile Salt Hydrolase, BSH)比酶活等一系列指标。用该标准对1株唾液乳杆菌和5株植物乳杆菌进行评估,结果显示6株菌在各项指标上都显示出菌株的特异性。6株乳杆菌中,植物乳杆菌Lp529在各方面都有优秀的表现,因此它被选出作为降胆固醇益生菌潜力株,并与1株商业菌株、植物乳杆菌LpOnlly一起,进行后续的研究。 研究Lp529和LpOnlly的BSH酶活发现如下特性: 1) BSH酶活不受其底物及底物组成基团激活或抑制,显示出BSH非变构酶的性质。 2) BSH总酶活累积曲线呈S型,与菌株生长曲线类似;BSH比酶活在菌株对数生长期时迅速升高,在平台期前达到峰值后又小幅回落并保持稳定。 3)模拟人胆汁短时间可逆调控BSH比酶活的高低。 4) 2株菌在模拟人胆汁中传代驯化,结果BSH比酶活逐代降低,并在第4代后达到最低值,仅为初始值的60%;同时降胆固醇能力也随之降低,而胆盐耐受性逐渐升高。 5)最后,通过引入BSH总酶活-胆固醇共沉淀曲线探讨并验证了乳杆菌降胆固醇作用的机理,为前述优良菌株的筛选提供理论支持。研究证实,菌株体外降胆固醇是共沉淀与同化共同作用的结果。在6株菌的去胆固醇效果中,同化作用都强于共沉淀。
[Abstract]:The cardiovascular disease caused by excessive intake of cholesterol is seriously harmful to human health, and how to control the serum cholesterol level has been paid more and more attention. Although the effect of Lactobacillus on cholesterol lowering has been reported widely, the evaluation criteria and clear removal mechanism of Lactobacillus strains are still uncertain. In this study, we first established a set of in vitro evaluation of Lactobacillus cholesterol lowering comprehensive performance. It includes the strain's tolerance to mimic gastric pH values, tolerance to simulated intestinal bile concentration, cholesterol lowering performance-including a separate evaluation of coprecipitation and assimilation, and bile salt hydrolase (Bile Salt Hydrolase, BSH) specific enzyme activity and a series of indicators. The standard was used to evaluate one Lactobacillus saliva and five Lactobacillus plantarum strains. The results showed that all the 6 strains showed the specificity of the strains in each index. Among the 6 strains of Lactobacillus, Lactobacillus plantarum Lp529 had excellent performance in all aspects. Therefore, it was selected as a potential strain of cholesterol-lowering probiotics and followed up with a commercial strain, Lactobacillus plantarum LpOnlly. The study of the BSH activity of Lp529 and LpOnlly showed the following characteristics: 1) the activity of BSH was not activated or inhibited by its substrate and substrates, which showed the character of BSH non-metamorphic enzyme. 2) the total enzyme activity accumulation curve of BSH was S-shaped, similar to the growth curve of strain, and the specific enzyme activity of BSH increased rapidly during the logarithmic growth period of the strain, then decreased slightly before the plateau stage and kept stable. 3) simulating the short time reversible regulation of BSH activity in human bile. 4) the two strains were subcultured and acclimated in simulated human bile. The results showed that the BSH activity was lower than the enzyme activity generation by generation, and reached the lowest value after the fourth generation, which was only 60% of the initial value, and the ability of lowering cholesterol was also decreased, and the tolerance of bile salt was gradually increased. 5) finally, the mechanism of cholesterol lowering by Lactobacillus was discussed and verified by introducing the BSH total enzyme activity-cholesterol coprecipitation curve, which provided theoretical support for the screening of the aforementioned excellent strains. It was confirmed that cholesterol reduction in vitro was the result of co-precipitation and assimilation. In the cholesterol removal effect of 6 strains, the assimilation was stronger than coprecipitation.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2008
【分类号】：R371
[Abstract]:The cardiovascular disease caused by excessive intake of cholesterol is seriously harmful to human health, and how to control the serum cholesterol level has been paid more and more attention. Although the effect of Lactobacillus on cholesterol lowering has been reported widely, the evaluation criteria and clear removal mechanism of Lactobacillus strains are still uncertain. In this study, we first established a set of in vitro evaluation of Lactobacillus cholesterol lowering comprehensive performance. It includes the strain's tolerance to mimic gastric pH values, tolerance to simulated intestinal bile concentration, cholesterol lowering performance-including a separate evaluation of coprecipitation and assimilation, and bile salt hydrolase (Bile Salt Hydrolase, BSH) specific enzyme activity and a series of indicators. The standard was used to evaluate one Lactobacillus saliva and five Lactobacillus plantarum strains. The results showed that all the 6 strains showed the specificity of the strains in each index. Among the 6 strains of Lactobacillus, Lactobacillus plantarum Lp529 had excellent performance in all aspects. Therefore, it was selected as a potential strain of cholesterol-lowering probiotics and followed up with a commercial strain, Lactobacillus plantarum LpOnlly. The study of the BSH activity of Lp529 and LpOnlly showed the following characteristics: 1) the activity of BSH was not activated or inhibited by its substrate and substrates, which showed the character of BSH non-metamorphic enzyme. 2) the total enzyme activity accumulation curve of BSH was S-shaped, similar to the growth curve of strain, and the specific enzyme activity of BSH increased rapidly during the logarithmic growth period of the strain, then decreased slightly before the plateau stage and kept stable. 3) simulating the short time reversible regulation of BSH activity in human bile. 4) the two strains were subcultured and acclimated in simulated human bile. The results showed that the BSH activity was lower than the enzyme activity generation by generation, and reached the lowest value after the fourth generation, which was only 60% of the initial value, and the ability of lowering cholesterol was also decreased, and the tolerance of bile salt was gradually increased. 5) finally, the mechanism of cholesterol lowering by Lactobacillus was discussed and verified by introducing the BSH total enzyme activity-cholesterol coprecipitation curve, which provided theoretical support for the screening of the aforementioned excellent strains. It was confirmed that cholesterol reduction in vitro was the result of co-precipitation and assimilation. In the cholesterol removal effect of 6 strains, the assimilation was stronger than coprecipitation.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2008
【分类号】：R371
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