After feeding lab mice a customized food made with bread provided by an artisanal bakery, researchers have learned more about how to produce “gut bacteria” that can help break down the nutrients in complex carbohydrates more efficiently. The findings may also lead to better treatments of yeast infections and Crohn’s Disease.
Bacteria that have evolved to help digest the yeast that give beer and bread their bubbles could support the development of new treatments to help people fight off yeast infections and autoimmune diseases such as Crohn’s disease, researchers report.
In the academic journal Nature, the University of Michigan Medical School, working with a dozen other microbiologists and chemists across the world, has published new research on the “gut bacteria” that helps people digest the yeast in beer and bread. For the study, laboratory mice were fed a customized food made with bread from Zingerman’s Bakehouse, a nationally known artisanal bakery.
The study’s findings may lead to better understanding of the unique way that bacteria help us obtain nutrients from the various foods we eat, the researchers say, by decoding yeast’s relationship with “good bacteria” and showing how microbes in our digestive tracts have learned to unravel the difficult-to-break-down complex carbohydrates that make up the yeast cell wall. the discovery of this process could accelerate the development of prebiotic medicines to help people suffering from bowel problems and autoimmune diseases, it was noted.
After evolving over the 7,000 years that people have been eating fermented food and drink, the ability of a common gut bacterium called Bacteroides thetaiotomicron to degrade yeasts is almost exclusively found in the human stomach, the researchers explain. The new findings, they add, provide a better understanding of how our unique intestinal “soup” of bacteria, the microbiome, has the capacity to obtain nutrients from our highly varied diet.
The study’s findings suggest that increasing the growth of Bacteroides in the microbiome can yield health benefits, and the research has helped to unravel the mechanism by which those Bacteroides learn to feast on difficult-to-break-down complex carbohydrates called yeast mannans.
Mannans, derived from the yeast cell wall, are a component in our diet from fermented foods including bread, beer, wine and soy sauce, as well as yeasts that call the microbiome home and are in some cases thought to be harmful.
“One of the big surprises in this study was that Bacteroides thetaiotaomicron is so specifically tuned to recognize the complex carbohydrates present in yeasts, such as those present in beer, wine and bread,” said Eric Martens, Ph.D., Assistant Professor in the University of Michigan Medical School’s Department of Microbiology and Immunology.
Researchers believed this mechanism emanated from the ability of common “gut bacteria” to recycle chemically similar carbohydrates present on intestinal cells, which are constantly being shed and renewed to keep the intestinal lining healthy.
“However, these bacteria turned out to be smarter than we thought: they recognize and degrade both groups of carbohydrates, but have entirely separate strategies to do so despite the substantial chemical similarity between the host and yeast carbohydrates,” Martens added. “Even the relatively small amounts of yeast that we commonly consume in foods are enough to impact the physiology of our friendly gut bacteria.”
The University of Michigan team tested this idea by feeding mice a diet consisting of 50 percent yeast-leavened bread baked at Zingerman’s Bakehouse in Ann Arbor, Mich. Bakehouse bread crumbs were used to create a customized mouse food. By working with an artisanal bakery, researchers were able to confirm the quantity of yeast consumed.
“People are very interested in developing dietary regimes where good bacteria are of benefit,” says Harry Gilbert, Ph.D., a senior author of the study. “When you have certain bacteria dominant in the gut, these microorganisms can produce molecules which have health-promoting effects.
“The more you understand about how complex glycans are degraded, the more you can think about developing sophisticated prebiotics that target the growth of specific beneficial bacteria,” Gilbert added.
The research could aid a better understanding of how to provide nutrients to specific organisms in the microbiome, the researchers said.