In Vitro Qualitative Assessment of Tolerance to Simulated Gastric Juice, Bile, Fructose, Glucose and Lactose for Different Probiotic Bacteria

Probiotics are live microorganisms that confer a health benefit to the host when administered in adequate amounts, with the main site of action at the intestinal level. In order to have a maximal effect, probiotic bacteria have to prove a high tolerance for the conditions present in the upper gastro-intestinal tract. The aim of the present study was to assess, from a qualitative point of view, the tolerance of different probiotic bacterial strains and combinations to simulated gastric juice, bile, fructose, lactose and glucose. Also, the influence of food on the bacterial growth after artificial digestion was analyzed. A bacteriologic assessment was realized for three different commercial probiotic products (Bacillus subtilis + Bacillus licheniformis + Pediococcus acidilactici; Enterococcus faecium; Bacillus subtilis + B. licheniformis + B.coagulans + B.indicus + B. clausii), simulating different conditions (artificial digestion method in the absence/presence of food, presence of bile, fructose, glucose, lactose). The obtained results suggested that the tolerance to simulated gastric juice is higher if the food is present in the moment of digestion, regardless of the probiotic bacterial strain or combination. Also, the tolerance to bile was different from one combination to another. The influence of fructose, lactose and glucose are not remarkable from a qualitative point of view. Moreover, the growth of different probiotic bacterial strains is influenced by the simulated gastro-intestinal conditions, sporulated bacteria presenting a slightly higher tolerance compared with non-sporulated strains.