Investigation of Acid and Bile Tolerance of Native Lactobacilli Isolated from Fecal Samples and Commercial Probiotics by Growth and Survival Studies

This study aimed at applying both growth and survival approaches to compare three native strains of lactobacilli, belonging to Lactobacillus plantarum, Lactobacillus rhamnosus and Lactobacillus acidophilus species, with two commercial probiotic strains in their tolerance to acid and bile. The association between the data obtained from the methods was studied.  The results of the different methods applied in this study, did not confirm each other for all the examined strains. However, the native strain of L. plantarum and the commercial strain of L. acidophilus repeatedly demonstrated the most and least bile resistances, respectively. The former excelled in all growth approaches but showed moderate acid resistance in the survival studies.  Bile stress seemed to have more detrimental effects on all examined strains. The overall results suggest that the growth-rate designed studies and survival studies evaluating transit tolerance, might bring up different results when the examined strains belong to different species of lactobacilli showing different growth and metabolic activities. The strain of L. plantarum examined here could thus be considered as a potential probiotic, regarding its overall resistance to acid and bile.