Journal of Food Science and Engineering 3 (2013) 196-206 Identification and Physiological Properties of Bifidobactérium Strains Isolated from Different Origin Fatima Mahmoudi, Hadadji Miloud, Guessas Bettache and Kihal Mebrouk Laboratory of Applied Microbiology, Department of Biology, Faculty of Science, University of Oran El-menaouer, BP 1524, Es-Senia Oran 31100, Algeria Received: December 31, 2012 / Published: April 20, 2013. Abstract: Bifidobacteria play an important role in maintaining human health, and suppress harmful bacteria by controlling the pH of the large intestine. About 14 strains of the Bifidobacteria have been isolated from the faeces of infants nursed exclusively from the maternal milk (their ages less than 5 months) from commercial French yoghurt (active bifidus] and from milk (celia bifidus) on MRS medium (containing 0.05% cysteine-HCl, with nalidixic acid 2 mg m -1 ). A total of six strain are strict anaerobic and gram-positive Bifidobacteria, identified as, B. longum (60% of the samples) was the most frequently found species, followed by B. bifidum (21.0%), B. breve (19%). These strains were evaluated for potential use as probiotics based on their adhesion to intestinal epithelial cells, resistance towards acidic (resistance to low pH) and bile conditions. pH values ranging from 6.5 to 7, however, these strains are sensitive to the pH 8, Bifidobacterium are mésophiles with optimal growth at 36 °C to 41 °C. All isolates studied have a fast growth in glucose. Key words: Probiotic, Bifidobacterium, acidity, survival, growth, isolate. 1. Introduction The human intestinal microbiota constitutes a complex ecosystem which is now well recognized for its impact on human health and well-being [1]. More than 400 species within the intestinal microflora can be identified and may attain population levels nearly as high as 10 12 g -1 in the colon [2]. Bifidobacteria were first discovered in infant feces by Tissier, who isolated a bacterium with a strange and characteristic Y shape and named it Bacillus bifidus [3]. From 1900 to 1957, This Bacteria are gram-positive pleomorphic, non-motile, non-spore-forming, nonmotile [4]. Anaerobic bacteria with spatulate extremities [5]. Bifidobacteria, are anaerobic, bacilli belonging to the dominant gut microbiota in humans and animals. In recent years, Bifidobacteria have gained a lot of attention because their association with Corresponding author: Fatima Mahmoudi, Ph.D., research fields: food and applied microbiology. E-mail: mahmoufati@yahoo.fr. numerous health-promoting effects, even though some mechanisms of these beneficial effects remain unexplained [6]. The Bifidobacteria play a fundamental role in the digestive ecosystem incited by several researchers to use these bacteria in prophylaxis and in therapeutic [7]. Recently, the isolation of Bifidobacterium species from feces has assumed considerable importance, as a consequence of interest in the potential health-promoting properties of this genus [8]. They are supported by bifidogenic factors presented in human milk. While in breast-fed infants bifidobacteria account more than 90% of the total intestinal bacteria, formula-fed infants’ flora is more diverse [9]. Moreover, the majority of the bifidobacterial species are host specific and it is recommended that the bifidobacterial strains used as probiotics should originally be isolated from the same species as the intended use ought to have an enhanced chance of survival. Many selection criteria were D DAVID PUBLISHING