This movie shows how a P. aeruginosa PAO1 biofilm deformed over time when held at an elevated shear stress. The biofilm was grown in a glass flow cell under turbulent flow at a flow velocity of 1 m/s. At high shears biofilms commonly form filamentous streamers which are attached to the solid surface by an upstream "head" while the "tail" is free to oscillate in the flow. The biofilm streamer stretched out when the flow velocity was turned up to 1.5 m/s and continued to elongate over time, demonstrating the viscous nature of the biofilm. During this time the biofilm was actually flowing like a viscous liquid. After 50 minutes the streamer tail broke away. Image analysis showed the formation of a neck region prior to failure. 

Klapper, I., Rupp, C.J., Cargo, R., Purevdorj, B., and Stoodley, P. 2002. A viscoelastic fluid description of bacterial biofilm material properties. Biotech. Bioeng. 80(3):289-296.

Stoodley, P., Cargo, R., Rupp, C.J., Wilson, S., and Klapper, I. 2002. Biofilm Material Properties as Related to Shear-Induced Deformation and Detachment Phenomena. J. Industrial Microbiol. Biotech. 29(6):361-368 (2002).

Further Reading:

Klapper, I., Rupp, C.J., Cargo, R., Purevdorj, B., and Stoodley, P. 2002. A viscoelastic fluid description of bacterial biofilm material properties. Biotech. Bioeng. 80(3):289-296.