传统酵素源高效降胆固醇菌株的筛选、鉴定及胆盐水解酶活性分析

目的:从传统酵素中分离出具有高效降胆固醇能力的菌株,并进行鉴定和降脂作用分析。方法:采用MRS、M17和PDA培养基筛选菌株,测定菌株胆盐耐受性、耐酸性、疏水性、自凝聚力、胆盐水解酶活性及降胆固醇能力,分析筛选菌株的降脂作用。结果:分离出51株菌,其中S-8、M-7、M-16菌的降胆固醇性能较好,胆固醇降低率分别为25.43%,37.06%,47.41%,胆盐耐受率分别为42.09%,65.64%,22.80%;S-8菌在二甲苯中疏水率高(35.91%),M-7菌在氯仿中的疏水率高(45.22%),这2株菌均具有较好的耐酸性和自凝聚力,静置24 h后,自凝聚力均在80%以上。测定S-8、M-7、M-16菌的降脂酶活力,发现降脂酶主要源于胞内酶,胞内酶的比活力是胞外酶的近7倍。结论:筛选获得3株具有高效降胆固醇能力的菌株,经形态学观察和16S rDNA序列分析,鉴定为副干酪乳杆菌和人葡萄球菌。本研究为进一步探明微生物对脂代谢的影响提供了试验依据。

Screening,Identification of Cholesterol-lowering Abilities of Strains from Traditional Ferments and Analysis of Bile Salt Hydrolase Activity

Objective:To isolate,identify and analysis the strains with high cholesterol-lowering activities from traditional ferments.Methods:Strains were screened by MRS,M17 and PDA culture media,and explore the tolerance of bile salt,acid resistance,hydrophobicity,self-cohesion ability,bile salt hydrolytic enzyme activity and cholesterol lowering properties.Results:51 strains were isolated from ferment,among which S-8,M-7 and M-16 had better cholesterol-lowering capacity and the cholesterol reduction rates were 25.43%,37.06%and 47.41%,respectively.The tolerance of bile salt tolerance were 42.09%,65.64%,22.80%;S-8 strain had the highest hydrophobicity in xylene,and the hydrophobicity was up to 35.91%,and the hydrophobicity of M-7 in chloroform was 45.22%.Both strains have good acid resistance and self-cohesion,after standing for 24 hours,the self-cohesion ability was more than 80%.The cholesterol-lowering effect was investigated.It was found that the intracellular enzymes were mainly responsible for this activity and had 7 times higher specific activity than the extracellular ones.Conclusion:Through the morphological observation and 16S rDNA molecular analysis,the S-8 strain was identified as L.paracasei strain,the other two strain were identified as Staphylococcus hominis strain.It is possible to further study microorganism on the regulation of lipid metabolism.