"For each human cell in your body there are 10 microbial cells, most of them living in the gut and helping us digest things we can't digest on our own," said Justin Sonnenburg, assistant professor of microbiology and immunology at the Stanford University School of Medicine.
Disorders such as inflammatory bowel disease, colorectal cancer and even obesity have been linked to skewed intestinal microbe distributions.
Scientists are hoping to remedy these disorders by manipulating microbial populations in the gut. Sonnenburg and his colleagues fed mice a diet rich in a particular complex carbohydrate that one bacterial species seemed genetically better equipped to digest, based on the presence of a small set of genes in its genome. As predicted, that bacterial species became predominant in the mice's intestines.
The results highlight the potential of prebiotics - adding substances to the diet in an effort to shift the mix of bugs in our gut in a healthy direction.
"Within one or two weeks, there was a significant change in the composition of the mice's gut communities," said Erica Sonnenburg, senior research scientist in Justin Sonnenburg's lab and first author of the study.
"We've now got germ-free mice to which we've introduced batches of bacteria representative of an entire human gut community in all its complexity," said Erica Sonnenburg.
The study is to be published June 25 in Cell.