Philip Strandwitz and his colleagues at Northeastern University in Boston discovered that they could only grow a species of recently discovered gut bacteria, called KLE1738, if they provide it with GABA molecules. “Nothing made it grow, except GABA,” Strandwitz said while announcing his findings at the annual meeting of the American Society for Microbiology in Boston last month.
GABA acts by inhibiting signals from nerve cells, calming down the activity of the brain, so it’s surprising to learn that a gut bacterium needs it to grow and reproduce. Having abnormally low levels of GABA is linked to depression and mood disorders, and this finding adds to growing evidence that our gut bacteria may affect our brains.
In this study, the researchers found that this effect vanished when they surgically removed the vagus nerve – which links the gut to the brain – suggesting it somehow plays a role in the influence gut bacteria can have on the brain.