Mechanical properties of the superficial biofilm layer determine the architecture of biofilms.
Cells in biofilms sense and interact with their environment through the extracellular matrix. The physicochemical properties of the matrix, particularly at the biofilm-environment interface, determine how cells respond to changing conditions. In this study we describe the application of atomic force microscopy and confocal imaging to probe in situ the mechanical properties of these interfacial regions and to elucidate how key matrix components can contribute to the physical sensing by the cells. We describe how the Young's modulus of microcolonies differs according to the size and morphology of microcolonies, as well as the flow rate. The Young's modulus increased as a function of microcolony diameter, which was correlated with the production of the polysaccharide Psl at later stages of maturation for hemispherical or mushroom shaped microcolonies. The Young's modulus of the periphery of the biofilm colony was however independent of the hydrodynamic shear. The morphology of the microcolonies also influenced interfacial or peripheral stiffness. Microcolonies with a diffuse morphology had a lower Young's modulus than isolated, circular ones and this phenomenon was due to a deficiency of Psl. In this way, changes in the specific polysaccharide components imbue the biofilm with distinct physical properties that may modulate the way in which bacteria perceive or respond to their environment. Further, the physical properties of the polysaccharides are closely linked to the specific architectures formed by the developing biofilm.
BioSystems and Micromechanics (BioSym) IRG, Singapore MIT Alliance for Research and Technology (SMART), Singapore.
Binu
B
Kundukad
Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore.
Thomas
T
Seviour
Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore and School of Biological Sciences, Nanyang Technological University, Singapore.
Yang
Y
Liang
Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore and School of Biological Sciences, Nanyang Technological University, Singapore and Centre for Marine Bio-Innovation and School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, NSW, Australia.
Scott A
SA
Rice
Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore and School of Biological Sciences, Nanyang Technological University, Singapore and Centre for Marine Bio-Innovation and School of Biotechnology and Biomolecular Science, University of New South Wales, Sydney, NSW, Australia.
Staffan
S
Kjelleberg
BioSystems and Micromechanics (BioSym) IRG, Singapore MIT Alliance for Research and Technology (SMART), Singapore and Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA. pdoyle@mit.edu.
Patrick S
PS
Doyle
D001419:Bacteria / Q000254:growth & development*; D018441:Biofilms; D055119:Elastic Modulus; D005109:Extracellular Matrix / Q000502:physiology*; D018625:Microscopy, Atomic Force