Vertical stratification of matrix production is essential for physical integrity and architecture of macrocolony biofilms ofEscherichia coli

    loading  Checking for direct PDF access through Ovid



Bacterial macrocolony biofilms grow into intricate three-dimensional structures that depend on self-produced extracellular polymers conferring protection, cohesion and elasticity to the biofilm. InEscherichia coli, synthesis of this matrix – consisting of amyloid curli fibres and cellulose – requires CsgD, a transcription factor regulated by the stationary phase sigma factor RpoS, and occurs in the nutrient-deprived cells of the upper layer of macrocolonies. Is this asymmetric matrix distribution functionally important or is it just a fortuitous by-product of an unavoidable nutrient gradient? In order to address this question, the RpoS-dependentcsgDpromoter was replaced by a vegetative promoter. This re-wiring ofcsgDled to CsgD and matrix production in both strata of macrocolonies, with the lower layer transforming into a rigid ‘base plate’ of growing yet curli-connected cells. As a result, the two strata broke apart followed by desiccation and exfoliation of the top layer. By contrast, matrix-free cells at the bottom of wild-type macrocolonies maintain colony contact with the humid agar support by flexibly filling the space that opens up under buckling areas of the macrocolony. Precisely regulated stratification in matrix-free and matrix-producing cell layers is thus essential for the physical integrity and architecture ofE. colimacrocolony biofilms.

Related Topics

    loading  Loading Related Articles