Commensal bacteria influence traits such as weight and behavior. But until now, researchers thought the bacteria that exerted these effects were acquired during a person's life. The study is the first to show that bacterial DNA can pass from parent to offspring in a manner that affects specific traits such as immunity and inflammation.
The researchers linked commensal bacteria in mice to the animals' susceptibility to a gut injury. Mice with certain inherited bacteria are susceptible to the injury, which is caused by exposure to a chemical. Female mice pass the bacteria to their offspring, making them vulnerable to the injury. Others carrying different bacteria are less susceptible.
In the short term, the findings may help scientists eliminate a significant "bug" in studies of genetically engineered mice. In several fields of research, scientists have been confronted intermittently with the sudden, unexplained appearance of new or altered traits in mice. The traits often spread from one mouse habitat to the next, suggesting a spreading microbial infection is responsible. But the traits also consistently pass from mother to offspring, suggesting a genetic cause.