为了筛选出具有高胆盐水解酶活性的乳酸菌,以生鲜牛奶为样品,利用传统分离技术分离乳酸菌,并通过牛津杯法选出具有高胆盐水解酶活性的乳酸菌,进而采用16S rDNA测序技术对筛选菌株进行鉴定。同时,研究pH、紫外照射时间、温度、培养基盐浓度和培养基糖浓度对所筛选菌株胆盐水解酶活性的影响。实验中分离出2株具有高胆盐水解酶活性的植物乳杆菌,为菌株N1和N12,胆盐水解酶高活性的最适pH为7、最适温度为59 ℃。菌株N1最适糖质量分数与最适盐质量分数分别为10%和7%,菌株N12最适糖质量分数与最适盐质量分数分别为5%和4%。植物乳杆菌N1和N12具有高胆盐水解酶活性,具有降解人体血清胆固醇的潜力,可应用于降胆固醇产品的开发。
In order to screen lactic acid bacteria(LAB) with high bile salt hydrolase (BSH) activity, fresh milk was used as the sample and LAB were isolated by traditional techniques. LAB with high BSH activity was screened by Oxford Cup method, then 16S rDNA sequencing was used to identify the strains. The effects of pH, UV exposure, temperature, and salt and sugar content in the medium on BSH activity of the strains were studied. The results showed that two Lactobacillus plantarum strains with high BSH activity were isolated, named N1 and N12, the optimal pH and temperature for BSH activity is 7.0 and 59 ℃, respectively. The optimum mass fraction of sugar and salt for N1 were 10% and 7%, respectively, and those for N12 were 5% and 4%, respectively. N1 and N12 have the potential to degrade serum cholesterol due to high BSH activity, and can be used in the development of cholesterol-lowering products.
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