In vitro simulation of the gastrointestinal tract environment and its interaction with probiotic lactobacilli

The harshest conditions of the human gastrointestinal tract were simulated in order to study probiotic bacteria in their intended environment. Eight Lactobacillus strains were cultivated in MRS broth with added bile in different concentrations and their growth was monitored as optical density. The gathered data was used to determine the MIC of bile for each strain. The recovery of the strains in MRS broth after 3 h in simulated gastric juice solution (pH 1.8, 5000 U/cm 3 pepsin) was investigated. Lactobacillus gasseri S20 exhibited the best survival rate and reached OD 600 0,490, while Lactobacillus acidophilus S11 could not survive the conditions of the stomach (OD 600 0,076).