Abstract
Probiotics provide important health benefits to the host by improving intestinal microbial balance and have been widely consumed as dietary supplements. In this study, we investigated whether Bifidobacterium lactis IDCC 4301 (BL), isolated from feces of breast milk-fed infants, is safe to consume. Based on the guidelines established by the European Food Safety Authority (EFSA), safety tests such as antibiotic susceptibility, hemolysis, toxic compound formation (i.e., biogenic amine and d-lactate), single-dose acute oral toxicity, and extracellular enzymatic activities were performed. In addition, toxigenic genes, antibiotic resistance genes, and mobile genetic elements were investigated by analyzing the genome sequence of BL. BL was susceptible to eight antibiotics except for vancomycin and the absence of transferable resistance in the genome of this strain implied that vancomycin resistance is likely to be intrinsic. With regard to phenotypic characteristics, there was no concern of toxicity of this strain. Furthermore, BL utilized various carbohydrates and their conjugates through the activity of various endogenous carbohydrate-utilizing enzymes. Interestingly, the supernatant of the BL showed strong antipathogenic activity against various infectious pathogens. Therefore, we suggest that BL should be a safe probiotic and can be used as a functional ingredient in the food, cosmetic, and pharmaceutical industries.