Bacteria that live within the human body use it as a "marketplace" to trade genes, allowing them to rapidly evolve new skills like antibiotic resistance, says Not Exactly Rocket Science's Ed Yong. A paper published recently in Nature shows that "our bodies turn out to be hotbeds of horizontal transfers," Yong says.
MIT researchers Chris Smillie and Mark Smith looked at the genomes of more than 2,200 bacterial species, and found that 10,000 genes had been recently swapped with other bacteria. Bacteria are more likely to exchange genes with other species living in the same area of the body, the researchers found. "In this way, ecology trumps history and geography. Bacteria that are separated by billions of years of evolution can still transfer genes to one another, as can species that live on different continents — what matters is that they share the same environment," Yong adds.
These swaps allow the microbes to adapt more quickly to the parts of the body in which they live. The researchers also identified 42 antibiotic-resistance genes that were introduced into the human microbiome from bacteria generally found in farm animals or food contaminants, Yong says. Smillie and Smith are hoping to identify the most beneficial bacterial genes — which spread quickly and allow the microbes to adapt quickly — which could provide insight into how the bugs develop resistance to antibiotics.