Bacteria that are unable to move on their own can hitch a lift on their mobile neighbours.

Yael Helman of the Hebrew University of Jerusalem and her team found that, on agar plates, the bacterium Xanthomonas perforans — which does not move on solid surfaces — triggered Paenibacillus vortex to move closer to it, and then used this travelling species as transport. This interaction occurred even when the two species were separated by a plastic barrier, suggesting that X. perforans releases an airborne substance to signal for a lift. Electron-microscope images revealed single X. perforans cells on 'rafts' of P. vortex.

This hitchhiking also occurred on leaves, and between other xanthomonads and motile bacteria, suggesting that the behaviour could be widespread.

ISME J. http://doi.org/q67 (2013)