乳酸菌富硒及产胞外多糖条件的研究

试验以实验室保藏的6株乳酸菌为研究对象,筛选出最佳试验条件下富硒率和产胞外多糖含量最优的菌株,以期为生产富硒调味品提供一定的理论依据。通过测定其生长曲线确定各菌的加硒时间,对比6株乳酸菌在不同亚硒酸钠质量浓度下的颜色变化、富硒率变化和胞外多糖含量变化,选定鼠李糖乳杆菌作为最佳试验菌株;通过测定鼠李糖乳杆菌在不同培养时间、培养温度、接种量、亚硒酸钠含量条件下富硒率和产胞外多糖含量的变化,通过此单因素试验确定了正交试验的因素及水平,由正交试验结果得到最佳试验条件。结果表明,培养时间24 h、接菌量5%、亚硒酸钠质量浓度12.5μg/mL、培养温度37℃的条件下,鼠李糖乳杆菌的富硒率为79.21%,胞外多糖含量为51.47μg/mL。

Study on Selenium Enrichment and Extracellular Polysaccharide Production Conditions of Lactic Acid Bacteria

In this experiment,six strains of lactic acid bacteria stored in the laboratory are selected as the research object,and the strains with the optimal selenium enrichment rate and extracellular polysaccharide content are screened out under the optimal experimental conditions in order to provide certain theoretical basis for the production of selenium-rich seasonings.The selenium addition time of the strains is determined by measuring the growth curves.The changes in color,selenium enrichment rate and extracellular polysaccharide content of six strains of lactic acid bacteria under different sodium selenite mass concentration are compared,Lactobacillus rhamnosus is selected as the optimal experimental strain.By measuring the changes in selenium enrichment rate and extracellular polysaccharide content of Lactobacillus rhamnosus under different culture time,culture temperatures,inoculation amount and sodium selenite content,the factors and levels of orthogonal test are determined through the single factor test,and the optimal test conditions are obtained from the results of orthogonal test.The results show that the selenium enrichment rate and extracellular polysaccharide content of Lactobacillus rhannosus are 79.21%and 51.47μg/mL under the conditions of culture time 24 h,inoculation amount 5%,sodium selenite mass concentration 12.5μg/mL and culture temperature 37℃.