为了筛选具有益生特性的优良菌株，该研究从健康婴儿粪便中分离筛选双歧杆菌，采用形态学观察、生理生化试验、基质辅助激光解吸电离飞行时间质谱（MALDI-TOF MS）及全基因组测序对筛选菌株进行鉴定，并通过人工胃肠液耐受实验、抗生素耐药性实验、急性毒性实验对其进行生物学表征。结果表明，分离筛选得到一株双歧杆菌BAL531，经鉴定，该菌株为乳双歧杆菌（Bifidobacterium lactis），其对14种常见肠道致病菌有较好的抑制效果，对9种常用抗生素敏感，经人工胃肠液处理后存活率均在55%以上，无口服及腹腔注射毒性反应。综上，乳双歧杆菌BAL531具有较好的胃肠液耐受性，并能够抑制肠道致病菌，且具有一定的安全性，可作为一株潜在的优良益生菌菌株进行深入研究。

In order to screen the superior strains with probiotic properties, Bifidobacterium was isolated from the feces of healthy infants and identified by morphological observation, physiological and biochemical tests, matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and whole genome sequencing. The screened strain was biologically characterized by artificial gastrointestinal fluid tolerance tests, antibiotic resistance tests and acute toxicity tests. The results showed that, a strain of Bifidobacterium BAL531 was screened, which was identified as Bifidobacterium lactis. It had good inhibitory effect on 14 common intestinal pathogenic bacteria and was sensitive to 9 commonly used antibiotics. The survival rates of strain BAL531 were above 55% after artificial gastrointestinal fluid treatments, and there were no oral and intraperitoneal toxic reactions. In summary, B. lactis BAL531 had a good tolerance to gastrointestinal fluid, and could inhibit intestinal pathogenic bacteria, and with a certain level of security, which could be a potential superior probiotic strain for further study.