This movie shows the rapid motion of motile cells in the interior of a P. aeruginosa biofilm microcolony growing in a glass lumen under laminar flow. After the initial formation of the microcolony, there is a phenotypic differentiation in which the cells on the outside of the colony form a "wall" while those on the inside become rapidly motile. In the next stage the motile cells flow out of the colony and spread across the wall of the flow cell with an appearance similar to that of a lava flow spreading from a side vent of a volcano.

Movie author: B. (Laura) Purevdorj and P. Stoodley