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Genetics hold far more sway over the mouse microbiome than transient environmental exposures, researchers reported July 26 in Applied and Environmental Microbiology. The results appear to contradict previous studies in humans that have found environmental factors to be more influential than genetics, and they add to an ongoing dialogue in the microbiome research community over how much control we hold over the bacterial communities in our guts.

Hila Korach-Rechtman, a microbiologist at the Israel Institute of Technology in Haifa, set out to identify the microbes in mice that become a fixture in the gut after being introduced through the environment. “We really wanted to find these bacteria that can be transferred and remain in the host, even though they have different genetics,” she says.