125 Vietnamese Journal of Food Control, Vol. 3, No. 2, 2020 Research Article * Corresponding author: Tel: 0947479978 Email: nmhuyen09@gmail.com Do Thi Men 1 , Pham Thi Le 1 , Tran Van Tuan 1 Ninh Thị Tuyet Lan 2 , Nguyen Thi Minh Huyen 2* 1 University of Science, Vietnam National University, Hanoi 2 Institute of Biotechnology, Vietnam Academy of Science and Technology, Hanoi (Received: 05/03/2020; Accepted: 30/06/2020) Abstract As one of the probiotic bacteria, Bifidobacterium is supplemented in the food industry such as in milk and yogurt. The advantageous impact of these bacteria on human health was reported. However, in Vietnam, the supplement of these bacteria as a probiotic source to the food was not much in the food industry. In our experiment, Bifidobacterium was isolated from a feces sample of 7 days-child which only had mother milk. The bacteria isolated from infant intestinal tract was Bifidobacterium infantis (B. infantis, closest to Bifidobacterium longum ssp. infantis strain Bi-26 with gene bank accession CP054425.1). The techniques to identify these bacteria were MALDI Biotyper, PCR, and sequencing. Our study is the first to isolate Bifidobacterium infantis in Vietnam. This experiment is original for further study of the characters of these bacteria to apply them in our daily life. Keywords: Bifidobacterium, isolation, identification, intestinal tract. 1. INTRODUCTION Bifidobacterium is a genus of Gram-positive, nonmotile, often branched anaerobic bacteria. They live in the gastrointestinal tract, vagina, and mouth of mammals, including humans. The uses of Bifidobacterium as probiotics are more and more popular all over the world. They are believed to have positive effects on human health [9]. Supplement of these bacterial strain into food has been used in food industry [10]. The bacteria cannot colonize the host themselves, therefore taken regularly for the benefits they confer can be accrued daily is neces- sary. The main effects of probiotic action were on infectious diarrhea and antibiotic-associated diarrhea, especially necessary in case of children who have been taken antibiotics to recover the good intestinal bacteria. The major mechanisms of action of probiotics are as following: (1) Enhancement of the epithelial barrier; (2) Increased adhesion to intestinal mucosa; (3) Inhibition of pathogen adhesion; (4) Competitive exclusion of pathogenic microorganisms; (5) Production of anti-microorganism substances; and (6) Modulation of the immune system [11]. Bifidobacterium was found mainly inhabitant in the infant gut. However at 2-year-olds, the strains were no longer detectable, may be due to the competition within the ecosystem over time [12]. These improved that supplement of these bacteria as probiotic regularly is necessary to keep healthy gastrointestinal tract. In our gut system, Bifidobacterium help to digest dietary fiber, prevent infection, and produce vitamins and other important chemicals. Bifidobacterium is believed to prevent and/or treat colorectal cancer in which it may reduce the occurrence of carcinogen-induced cancerous cells in mice. The treatment of diarrhea using Bifidobacterium Isolation and identification of Bifidobacterium spp. from infant intestinal tract