Numerous criteria have been defined for the selection
of probiotic strains (reviewed in 11). Obviously, the most
important criterion is that selected strains have to be safe
for use in the host and for the environment. One of the
most commonly reported selection criteria is the ability to
survive during passage through the gastrointestinal tract
(GIT) of the host for which the capacity of a strain to
withstand the conditions prevailing in the stomach (high
acid level) and intestinal tract (bile acids, pancreatic and
other digestive enzymes) is crucial.