How Bread, Beer, and Soy Sauce Changed the Human Microbiome
6th February 2015
Digesting yeast is no mean feat. Yeast surround themselves with a difficult-to-digest structure called a cell wall. Yet common gut bacteria called Bacteroides thetaiotaomicron are able to munch their way through a complex carbohydrate, called alpha-mannan, that appears in the cell walls of bread and brewer’s yeast, researchers have found. A team of biologists and chemists from research centers in Europe and the U.S. ran the study by growing different gut bacteria species in a lab and feeding them only yeast-made mannan. Those bacteria that didn’t die must have been surviving on the mannan, the team concluded. Further tests revealed the complex chemical processes the bacteria used to break down alpha-mannan, a molecule that few other micoorganisms are able to digest.