Bifidobacteria undoubtedly like resistant starch (RS). They bind and hold on tight, an effect mediated by cell surface proteins. Big thanks to Tim Steele for passing along many of the studies cited here. One of said studies showed that treatment of bifidobacteria with proteases abolished the RS binding; but even dead critters would bind if their cell surface proteins were intact (Crittenden et al., 2007).
I suspect fermented foods have this all figured out. The microbes in sauerkraut are going to be embedded in & all around the cabbage polysaccharides; likely protected from digestive enzymes (to a degree) and holding on tight.
Something similar has been shown for galactooligosaccharides
These mechanisms are likely not mutually exclusive, and both seem like they could benefit the host (us).
can help, too, if they’re administered with either prebiotics or fermented foods (they need something to nourish them in transit). 
condition. They were then given 4 eggs (~23 g protein) that were labeled with two stable isotopes (15N & 13C, derived from hens fed isotope-enriched diets!). Throughout the entire study duration, the subjects were infused with a third isotope, 2H-glucose. By collecting and analyzing the enrichment of isotopically-labeled metabolites like expired CO2, urea, and glucose, the researchers were able to determine the fate of those 23 grams of protein.
et al., 1997)
= pharmaceutically enhanced low fat diet. 
