This considerable reduction is also close to what was observed for L. acidophilus La-5 submitted to similar assay conditions. On the other hand, the authors reported a remarkably higher resistance of B. animalis Bb-12, which maintained counts above 7 log CFU/g after 6 h of exposure to gastrointestinal conditions. Even though many other factors should be considered, in general, Gram-positive bacteria like bifidobacteria seem to be less resistant to the deleterious effects of bile. One of the possible mechanisms by which bile affects probiotic cells would be through membrane-damaging effects and/or disrupting the cell stability. Despite this fact, bile tolerance is a strain-specific characteristic and therefore, it cannot be generalized. In addition, Begley et al. (2005) remind that the concentration of bile acid varies from one
person to the other and, in general, experimental assays are not able to simulate the exact bile composition found in humans