Schretter, C.E., et al. Nature 563, 402–406 (2018)

The microbiome could be behind it all, at least in fruit flies. Disrupting the fly gut microbiome can have profound impacts on locomotion, suggests a new study from researchers at the California Institute of Technology.

Female fruit flies with a conventional, un-tampered-with gut microbiome walk in a characteristic way. But eliminate those microbes and locomotion change—axenic flies, raised to be free of any microbes, walk faster and with fewer pauses than their conventional counterparts. By selectively adding different bacteria and molecules to germ-free flies, the researchers tested which component of the microbiome was influencing locomotion. They observed links to one commensal bacterium in particular, Lactobacillus brevis, and a specific enzyme it produces that modulates sugar metabolism in the flies.