The following study is one of my favorites!
Imagine this: Not just between humans but also between mice there are different personalities and for an experiment, researchers used two extremes of mice - Brave mice and Shy Mice.
The characteristics were defined by a so-called step-down test where a mouse is placed in the center of an elevated platform and the time the mouse needs to step down is measured.
The brave mice usually needed less than 20 seconds to jump down while the shy mice needed three times as much time to do so. To identify whether these behaviors have anything to do with the microbiome, they fed the mice antibiotics to deplete their microbes.
After the antibiotica treatment, they specifically re-introduced in the brave mice the microbiome from the shy mice or they "gave back" the brave mice the microbiome from the brave mice. Next, they repeated the step down test and the results were astonishing:
The brave mice, who now harbors the microbiome from shy mice suddenly needs the same time to step-down as the shy mice needed before.
It is like the microbes would have carried over the characteristic traits of the mice.
- Bercik et al., The intestinal microbiota affect central levels of brain-derived neurotrophic factor and behavior in mice, Gastroenterology, 2011