Inside your gut is a complex ecosystem: bacteria that are crucial to the digestive process, along with bacteria-invading viruses whose role is largely unknown. A genetic analysis conducted by microbiologist Jeffrey Gordon at Washington University in St. Louis offers one of the first comprehensive descriptions of this inner world. More than 80 percent of the viral gene sequences he found were new to science.
Gordon’s group took fecal samples from four sets of identical twins and analyzed their microbes. The mix of viral genes he found was unique to each individual. Each one’s gut virome was also very stable: Samples taken a year apart shared 95 percent of the same viral genes, Gordon reported in Nature last July. The stability of the gut population and the specific viral genes that turned up there suggest that the relationship between the bacteria and the viruses is mutualistic. The samples included many viral genes that, when incorporated into a bacterium, can aid metabolism.
The gut microbial community is effectively an “organ within an organ,” Gordon says. The mix of microbes inside you affects how you metabolize food and probably has substantial impact on your health. In the future doctors may pay more attention to tending the microbes within us. “Considering ourselves as a composite of species will be an important step” for better health care, Gordon says.