Microbiota transmission

Mammals house a diversity of bacteria that affect health, but the routes by which bacterial lineages are transmitted between hosts remain poorly understood. We experimentally delineated microbiota-transmission modes by deriving 17 inbred mouse lines from two wild populations and monitoring their gut microbiotas for ten host generations. Individual- and population-level microbiota variation was maintained within lines throughout the experiment, indicating vertical microbiota inheritance. However, certain bacterial taxa tended to be exchanged horizontally. In line with evolutionary theory, the degree of horizontal transmission predicted rates at which genera cause infections and hospitalizations in humans, according to epidemiological data. These results reveal transmission modes in the mammalian gut microbiota and indicate that human bacterial pathogens belong to genera that are well-adapted for horizontal transmission in indoor environments.