In the study, conducted in previously germ-free mice, colonization with two prominent human gut microbes led to fatter mice. Scientists at Washington University School of Medicine in St. Louis called the results an illustration of how understanding the menagerie of microorganisms that live in our guts can provide new insights into health. The study is will be published online by the Proceedings of the National Academy of Sciences.

To one day consider manipulating gut microbes for medical benefits, such as weight loss or gain, scientists need to know who's living in our digestive systems and how they form strategic alliances with one another to benefit themselves and us. They also have to learn how much this cast of microbial characters varies in different human individuals.

"We are superorganisms containing a mixture of not just human cells but also bacterial cells and cells of another microscopic domain of life known as Archaea," says senior author Jeffrey Gordon, M.D., the Dr. Robert J. Glaser Distinguished University Professor. "As adults, the number of these bacterial and archaeal microbial cells exceeds the number of our human cells by tenfold. The genes present in this community of 10-100 trillion bugs vastly outnumber our own genes and are a key part of our genetic landscape, providing us with attributes we have not had to evolve on our own."

One such attribute is the ability to digest commonly consumed complex sugars known as polysaccharides. Many types of polysaccharides pass through the small intestine mostly unchanged because our human genome does not have the genes needed to digest them. Bacterial partners living
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Contact: Michael C. Purdy
purdym@wustl.edu
314-286-0122
Washington University School of Medicine
12-Jun-2006