Host specificity
It is often stressed that probiotics should originate from the
same host as they are intended for (4, 82). However, it is still
uncertain to what extent host specificity plays a role in the
functioning of probiotics. We have, in fact, observed that
probiotics isolated from humans bind at a similar level to
intestinal mucus from dogs (58), rainbow trout (59), pig (43)
and humans (54). This still remains to be investigated for
other parts of the mucosa such as epithelial cells, although
propionibacteria of dairy origin have been observed to
adhere to mouse intestinal cells (12)