A study was conducted to isolate lactobacilli from the gastrointestinal (GI) tract of broiler chickens and to evaluate their application as a probiotic supplement. The GI contents of 12 broiler chickens from three different ages were collected and cultured on Man Rogosa and Sharp (MRS) agar. In order to determine bacterial species, different grown colonies were separated and subjected to the sequencing of the 16s ribosomal DNA fragment. An auto-aggregation test was performed for 39 isolated lactobacilli bacteria. Eight species were selected because of their convenient aggregation. In vitro tests including antibacterial activity, resistance to low pH, resistance to bile extract, ability to produce H O , cell surface hydrophobicity and adhesion activities on crop epithelial cells were performed for evaluating of probiotic potential for each strain. These tests were ranked according to their priority for probiotic strains. The total score obtained from different experiments is indicator of suitable strain. Under the in vitro conditions and with respects to the probiotic traits, Lactobacillus salivarius caeca4 and Lactobacillus crispatus caeca10 were suggested as probiotic strain, and can be evaluated in an in vivo conditions of commercial birds.

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