降胆固醇乳酸菌的筛选、鉴定与益生特性评价

Screening and Identification of Cholesterol-lowering Lactic Acid Bacteria and Evaluation of Their Probiotic Characteristics

目的:从婴儿粪便和发酵食品中筛选具有高效降胆固醇能力且益生特性优异的乳酸菌。方法:从20份婴儿粪便、8份传统发酵泡菜和4份金华火腿样品中初步筛选到乳酸菌102株,采用气相色谱法测定供试菌株的降胆固醇能力,菌株ZY08和I631的降胆固醇能力显著高于(P<0.05)标准菌株(ATCC 43121);采用16S rDNA测序对这2株乳酸菌进行鉴定,评价菌株的酸耐受性、胆盐耐受能力、抗生素敏感性及抗菌活性。结果:筛选得到2株高效降胆固醇乳酸菌:植物乳杆菌ZY08和发酵乳杆菌I631,胆固醇降低率分别为67.45%和63.19%。在pH 1.5和pH 3.0的条件下培养6 h,菌株ZY08和I631的活菌数均大于6 lg(CFU/mL)。2株菌对3,5及1.0 g/L胆盐具有一定的耐受性,胆盐耐受能力均在80%以上(胆盐含量为3 g/L);对常见的8种抗生素(青霉素、氨苄青霉素、头孢唑林、丁胺卡那、庆大霉素、红霉素、复方新诺明、氯霉素)都不具备耐药性,对人体健康不存在潜在威胁;2株菌的代谢产物对4种肠道致病菌(金黄色葡萄球菌、单核细胞增生李斯特菌、大肠杆菌O157∶H7、鼠伤寒沙门氏菌)具有一定的抑制作用。结论:获得具有高效降胆固醇能力的植物乳杆菌ZY08和发酵乳杆菌I631,为功能性乳制品的开发提供菌株来源。

Objective:The aim of the study was to screen lactic acid bacteria(LAB)with high cholesterol-lowering ability and great probiotic properties,from fermented food and infant feces.Methods:102 LAB strains were collected from 20 infant feces,8 traditional fermented pickles and 4 Jinhua ham samples.The cholesterol-lowering ability of strain ZY08 and I631,tested by gas chromatography method,was significantly higher than that of standard strain(ATCC 43121)(P<0.05),and were identified by 16S rDNA sequencing.The acid tolerance,bile salt tolerance,antibiotic sensitivity and antimicrobial activity of the two strains were evaluated.Results:Two probiotic strains with high cholesterol-lowering ability were screened:Lactobacillus plantarum ZY08 and Lactobacillus fermentans I631,and the cholesterol reduction rates were 67.45%and 63.19%,respectively.After incubation at pH 1.5 and 3.0 for 6 h,the viable bacteria numbers of strains ZY08 and I631 were greater than 6 lg(CFU/mL);the two strains had a certain tolerance to 3,5 and 10 g/L bile salt and the tolerance to bile salt was over 80%(3 g/L bile salt);they were sensitive to the 8 kinds of antibiotics(penicillin,ampicillin,cefazolin,amikacin,gentamicin,erythromycin,sulfamethoxazole,chloramphenicol),and had no potential threat to human health.The fermentation supernatant of these two strains had a certain inhibitory effect on four intestinal pathogenic bacteria(Staphylococcus aureus,Listeria monocytogenes,Escherichia coli O157∶H7,Salmonella typhimurium).Conclusion:Lactobacillus plantarum ZY08 and Lactobacillus fermentans I631 with probiotic potential were obtained in this experiment,which could provide a source of strains for development and research of functional dairy products.