Mehri Joghataei - Department of Food Science and Technology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.
Gholamreza Pouladfar - Professor Alborzi Clinical Microbiology Research Center, Nemazee Hospital, Shiraz University of Medical Sciences, Shiraz, Iran.
Abbasali Ghaderi - Department of Immunology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran.
Fakhri Shahidi - Department of Food Science and Technology, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran.

Introduction and Objectives: Traditional fermented products are a rich source of microorganisms which may have remarkable probiotic properties even more significant than probiotic strains of human origin. Materials and Methods: In this study three Lactobacillus plantarum and one Lactobacillus fermentum strains, isolated from either Iranian traditionally fermented products or children’s feces identified with molecular methods and selected, based on high acid resistance, were investigated for their probiotic properties in vitro and compared with standard probiotic strains of their species; L. plantarum ATCC 14917, L. fermentum PTCC 1744 and L. acidophilus ATCC 4356. Results: Most of the isolates showed a high survival rate under gastrointestinal tract conditions and L. plantarumstrains displayed a moderate ability to adhere to HT-29 cells. Neutralized cell free culture supernatants of L. plantarum strains were capable of inhibiting pathogensincluding E. coli O157:H7and Salmonella typhimurium ATCC 14028. Almost all of the strains were resistant to vancomycin and streptomycin and susceptible to other clinically relevant antibiotics. Isolated strains exhibited low to moderate auto aggregation (Auto-A), co-aggregation (Co-A) and hydrophobicity, following a strain specific manner. None of the strains invaded into HT-29 cells while strain PF11 could significantly decrease the number of adhering pathogenic bacteria. Most of the strains increased apoptosis of HT-29 cells, though they had no effect on HUVEC cells.Conclusion: Favorable probiotic properties of strains PL4, PT10 and PF11 along with their apoptotic activity imply their potential for clinical or technological applications. However, further in vitro/in vivo investigations are recommended.