Characterization of Intestinal Lactobacillus reuteri Strains as Potential Probiotics

This study was conducted to evaluate the probiotic properties of Lactobacillus reuteri isolated from human infant feces (less than 3 months). Out of thirty-two representative L. reuteri strains isolated from the infant human feces, nine isolates (i.e. LR5, LR6, LR9, LR11, LR19, LR20, LR25, LR26 and LR34) showed survival in acid, bile and simulated stomach-duodenum passage conditions, indicating their high tolerance to gastric juice, duodenal juice and bile environments. The nine isolates did not show strong hydrophobic properties because the percentages of adhesion to the apolar solvent, n-hexadecane, did not exceed 40%, showing that their surfaces were rather hydrophilic. Functionality of these nine probiotic isolates was supported by their antagonistic activity and their ability to deconjugate bile salts. The safety of the nine indigenous L. reuteri isolates was supported by the absence of transferable antibiotic resistance determinants, DNase activity, gelatinase activity and hemolysis. The results obtained so far suggest that the nine strains are resistant to low pH, bile salts and duodenum juice, so they could survive when passing through the upper part of the gastrointestinal tract and fulfill their potential probiotic action in the host organism. According to these results, the L. reuteri strains isolated from human infant feces possess interesting probiotic properties that make them potentially good candidates for probiotics.