Bacteria that give beer bubbles may fight disease

Bacteria that help us digest the yeast that give beer and bread their bubbles could support the development of new treatments to help people fight off infections and autoimmune diseases, researchers say.
The study shows how microbes in our digestive tract have learned to unravel the difficult to break down complex carbohydrates that make up the yeast cell wall.
Evolving over the 7,000 years that we 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 gut.
The international research team says the discovery of this process could accelerate the development of prebiotic medicines to help people suffering from bowel problems and autoimmune diseases.

The study, led by Harry Gilbert, professor of biochemistry at Newcastle University; Eric Martens, of the University of Michigan's Department of Microbiology and Immunology, and Wade Abbott, research scientist at Agriculture and Agri-Food Canada, has identified the complex machinery that targets yeast carbohydrates.
The new findings provide a better understanding of how our unique intestinal soup of bacteria - termed the microbiome - has the capacity to obtain nutrients from our highly varied diet. The results suggest yeast has health benefits possibly by increasing the Bacteroides growth in the microbiome.

The research has unravelled the mechanism by which B thetaiotaomicron has learned to feast upon 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 B thetaiotaomicron is so specifically tuned to recognise the complex carbohydrates present in yeasts, such as those present in beer, wine and bread," said Martens.
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 recognise 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 said.
The study was published in the journal Nature.