Issue: March 2015
January 09, 2015
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Yeast-Consuming Gut Bacteria may Aid Development of Prebiotic Treatments

Issue: March 2015
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Researchers have identified the complex relationship between a particular strain of human gut bacteria and the yeast it has evolved to consume, and they say their findings could aid in the development of prebiotic treatments for inflammatory bowel disease and other autoimmune disorders.

Prebiotics are dietary components that encourage the growth of beneficial bacteria in our gut microbial community (defined as the microbiota),” Harry J. Gilbert, PhD, BSc, from the Institute for Cell and Molecular Biosciences at Newcastle University, told Healio Gastroenterology. “The most effective prebiotics are complex carbohydrates that escape digestion by our intestinal enzymes. Understanding how these complex carbohydrates are degraded will provide a better understanding of how to provide nutrients to specific organisms in the microbiota.”

Harry J. Gilbert, PhD, BSc

Harry J. Gilbert

Using detailed biochemical analysis, targeted gene disruption studies, co-culturing studies and genomic comparison, Gilbert and colleagues essentially identified the distinct mechanism by which a specific gut bacterium metabolizes yeast.

 “In this study we show that an important human gut bacterium, Bacteroides thetaiotaomicron, can degrade alpha-mannan, the major polysaccharide in the yeast wall through a non-sharing or selfish mechanism,” Gilbert said.

Mannans are derived from the cell wall of yeast, which are part of the human diet in the form of fermented foods like bread, beer, wine and soy sauce, according to a press release. Bacteroides thetaiotaomicron have evolved over the 7,000 years that humans have been consuming fermented foods, and thus their ability to break down yeast is “almost exclusively found in the human gut,” the release said.

“By consuming carbohydrates that we can’t, which they convert to short-chain fatty acids that they secrete into our distal gut, these bacteria establish a symbiosis that nourishes the cells that line our gut wall and provide important immune signals that establish a healthy immune response,” Spencer Williams, PhD, BSc, from the University of Melbourne, said in the release.

The investigators hope their research may contribute to greater understanding of how to provide nutrients to these and other beneficial bacteria in the microbiome, the release said.

“Given that the bacterium (Thetanix, GT Biologics) has been granted Orphan Designation by the FDA for pediatric Crohn’s disease, yeast mannan may have health-promoting effects on the microbiota by stimulating the growth of Bacteroides thetaiotaomicron,” Gilbert said.

Disclosure: The researchers report no relevant financial disclosures.