For more than 100 years, scientists have known that humans carry a rich ecosystem within their intestines. An astonishing number and variety of microbes, including as many as 400 species of bacteria, help humans digest food, mitigate disease, regulate fat storage, and even promote the formation of blood vessels. By applying sophisticated genetic analysis to samples of a years worth baby poop, Howard Hughes Medical Institute researchers have now developed a detailed picture of how these bacteria come and go in the intestinal tract during a childs first year of life.
The study, published June 25, 2007, in the journal Public Library of Science (PLoS) Biology, was led by Howard Hughes Medical Institute (HHMI) investigator Patrick O. Brown at the Stanford University School of Medicine.
"I don't know what a human would look like without a colonized gut," said Chana Palmer, the lead author of the new study and a former graduate student in Brown's lab. "The microbiota are important. They help you extract more from your food; they're important for the immune system; and they help protect us from being colonized by [microbes] that are going to do us harm."
Before birth, the human intestinal tract is sterile, but babies immediately begin to acquire the microbial denizens of the gut from their environment -- the birth canal, mothers' breast, and even the touch of a sibling or parent. Within days, a thriving microbial community is established and by adulthood, the human body typically has as many as ten times more microbial cells than human cells. This is primarily due to the large number of microorganisms that have taken up residence in the intestine.
The new study tracked the evolution of the microbial ecosystems in 14 healthy, full-term human infants that were breast fed. Most of the bacteria that live within humans do not thrive in an oxygen-rich environment, and thus are difficult or impossible to grow in culture in the lab. So th
Contact: Jennifer Michalowski
Howard Hughes Medical Institute