Myxococcus xanthus is a predatory bacterium that exhibits various collective behaviors throughout its lifecycle. At left, M. xanthus cells self-organize into traveling waves when preying upon E. coli. At right, in areas without prey, M. xanthus self-organizes into haystack-shaped spore-filled structures.
That's the winning formula of one of the world's smallest predators, the soil bacteria Myxococcus xanthus, and a new study by scientists at Rice University and the University of Texas Health Science Center at Houston (UTHealth) Medical School shows how M. xanthus uses the formula to spread, engulf and devour other bacteria. The study, featured on the cover of this month's online issue of the journal PLOS Computational Biology, shows how the simple motions of individual bacteria are amplified within colonies of M. xanthus to form millions-strong waves moving outward in unison.
The findings answer longstanding questions about how the waves form and the competitive edge they provide M. xanthus. "When the cells at the edge of the colony are moving outward, they are unlikely to encounter another M. xanthus cell, so they keep moving forward," said lead author Oleg Igoshin, assistant professor of bioengineering at Rice. "When they are traveling the other way, back toward the rest of the colony, they are likely to encounter other cells of their kind, and when they pass beside one of these and touch, they get the signal to turn around." Igoshin said the net effect is that the cells "spend more time moving outward than inward, and as a result, they spread faster."