Gastrointestinal biofilms are an important topic, and those comprised of pathogenic microbes are getting much well-deserved attention in the integrative medical community. However, in keeping with the sIgA topic, I want to give a shout-out to commensal biofilms, which are vital to GI health and deserve similar attention.
Biofilms are everywhere, allowing bacteria to survive -- good or bad. They are found at the solid-liquid interface in most environments. Indeed, dental plaque is a biofilm, as is the slime on an icky bathtub. Biofilms are comprised of bacteria (and/or other microbes) and an extracellular matrix of excreted polymeric polysaccharides.
Simply put: bugs + goo = slime (biofilm).
Slime is nothing to joke about! Biofilms allow pathogenic organisms to be antibiotic resistant, up to 1000-fold by one estimate. But biofilms comprised of commensals can be our friends, modulating our immune response, supporting GI integrity and reducing inflammation.
Research on commensal GI biofilm shows that E. coli , bifidobacteria and L. reuteri are apparently efficient producers, with the former mediated by sIgA and mucin. Research suggests commensal biofilms may be anti-inflammatory, modulate cytokine production and crowd out pathogenic biofilms.
One study in rats with human-type flora showed improved bifidobacteria biofilm, mucus thickness, villous height, crypt depth, and mucin-producing goblet cell numbers when supplemented with inulin-type fructans. How cool is that?
How can we tell if our GI commensal biofilm is healthy?
On a stool test, I would be concerned if I didn’t see enough bifidobacteria, lactobacillus, commensal E. coli or sIgA. Glutamine, vitamin A and S. boulardii support sIgA production; whereas the inulin mentioned above, plus probiotic supplementation, will help facilitate commensal bacterial growth. Finally, treating inflammation and minimizing unwarranted antibiotic use should also benefit biofilm status.
I think we can say that biofilms are little ecosystems unto themselves, where "the sum is greater than the parts.” And when we’re thinking about protection of our all-important GI microbiota, the commensal biofilm is once slimy surface we don’t want to slip away!