Probiotics colonic survival

A critical criterion of selection is that the probiotic strain must be tolerated by the immune system and should not provoke the formation of antibodies against the probiotic. This latter property, in conjunction with the ability of some LAB to survive and colonize in the gut, has given rise to further applications, which involve their use as live vectors for oral immunization, i.e., introducing antigens targeting the GALT and aiming to induce a mucosal immune response (Marteau and Rambaud, 1993). 

Second, probiotics must be delivered at an effective dose. In the gut, the resident microbiota clearly outnumbers administered probiotic microorganisms and this may reduce the chances of probiotics having a major impact on the microbial ecology of the gut environment. A number of viable cells are required to be able to survive gastric transit, to resist the action of bile salts and then reproduce within the gut to ensure a colonization rate sufficient to provide the expected beneficial effects. 

Survival of probiotics imder various physicochemical conditions that are imposed during both processing and after intake (in the gastrointestinal tract) varies between strains. This needs further explanation and inter-species differences more fuUy determined and explained. This will lead to focusing upon the most reliable strains. For probiotics, nomenclature (taxonomical changes), poor stability and inaccurate labelling make sound conclusions difficult. Similarly there is no consensus on what constitutes a transient, persistent or colonizing effect within the gut flora. 

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