高产共轭亚油酸的植物乳植杆菌YYS-99筛选及特性研究

Screening and Characteristic Study of Lactiplantibacillus plantarum YYS-99 with High Yield of Conjugated Linoleic Acid

目的:筛选1株高产共轭亚油酸的乳酸菌应用于工业化生产。方法:采用光度计检测法测定实验室菌库中300株乳酸菌生物转化共轭亚油酸的能力,从中筛选1株产共轭亚油酸最优的乳酸菌,经形态学观察、生理生化实验、16S rRNA序列测定对该乳酸菌进行鉴定。采用牛津杯法,测定该乳酸菌对食源性致病菌的抑菌谱。通过体外模拟人工胃液和肠液环境,测定该乳酸菌在不同pH值胃液下的耐酸性和不同胆盐质量浓度肠液下的耐胆盐性。结果:在底物亚油酸浓度为0.5 mg·mL^(-1)时(LA+MRS),成功筛选出1株转化生成共轭亚油酸的量显著高于其他菌株的乳酸菌,产量为205.4μg·mL^(-1),转化率约为41.1%。该乳酸菌经鉴定为植物乳植杆菌(Lactiplantibacillus plantarum),命名为YYS-99。YYS-99对宋内氏志贺氏菌的抑菌圈直径最大,为(16.84±0.32)mm。在体外模拟人工不同pH值胃液和不同胆盐质量浓度肠液下,YYS-99均具有较高的活菌数和存活率。结论:本研究从菌库筛选出1株高产共轭亚油酸的植物乳植杆菌(YYS-99),其对食源性致病菌有明显的抑制作用,且对不同pH值下的胃液和不同质量浓度胆盐下的肠液均具有良好的耐受性。

Objective:Screening out one lactic acid bacteria with high yield of conjugated linoleic acid and applying it to industrial production.Method:The ability of 300 strains of lactic acid bacteria in the laboratory microbial bank to biotransformation conjugated linoleic acid was measured by ultraviolet spectrophotometer detection method,and one strain of the best lactic acid bacteria producing conjugated linoleic acid was screened out.The lactic acid bacteria were identified by morphological observation,physiological and biochemical experiments and 16S rRNA sequencing.Then the Oxford cup method was used to determine the bacteriostatic spectrum of the lactic acid bacteria against foodborne pathogens.Finally,the acid resistance of the lactic acid bacteria under different pH values of gastric juice and the bile salt resistance under different bile salt mass concentrations of intestinal juice were determined by simulating the artificial gastric juice and intestinal juice environment in vitro.Result:When the concentration of substrate linoleic acid was 0.5 mg·mL^(-1)(LA+MRS),one strain of lactic acid bacteria was successfully screened,and the amount of conjugated linoleic acid(CLA)produced by the transformation was significantly higher than that of other strains,which yield was 205.4μg·mL^(-1),and the conversion rate was about 41.1%.The lactic acid bacteria was identified as Lactiplantibacillus plantarum and named YYS-99.The bacterial YYS-99 has the largest inhibitory zone diameter against Shigella sonnei,which is(16.84±0.32)mm.YYS-99 showed good viabilit and survival rate under different pH of artificial gastric fluid and different concentration of bile salt in intestinal fluid.Conclusion:In this study,a strain of Lactiplantibacillus plantarum YYS-99 with high yield of conjugated linoleic acid was screened from the microbial bank.It showed obvious inhibition against foodborne pathogenic bacteria,and showed good tolerance to gastric fluid under different pH and intestinal fluid under different mass concentration of bile salt.