This movie shows the elasticity of cell clusters in a P. aeruginosa FRD1 biofilm. FRD1 is a mucoid cystic fibrosis isolate. The biofilm was grown in a glass flow cell under a fluid shear stress of 0.007 N/m2. When the flow was turned up (see top left panel for hydrodynamic details - flow velocity, Reynolds number and theoretical fluid shear stress) the clusters elongated in the downstream direction. When the flow was turned back down they contracted demonstrating an elastic response. More difficult to see in this movie is the residual strain (the clusters end up being slightly longer than they were originally) indicating that the biofilm actually flowed during exposure to elevated shear stress. The movie was taken over an approximate 3 minute period. 

Shear Induced Detachment

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.