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Mechanical Principles of Biofilm Formation

Speaker

Jing Yan, Princeton University

Time

2017.05.25 10:00-11:30

Venue

601 Pao Yue-Kong Library

Abstract

Biofilms are surface-associated bacterial communities embedded in an extracellular matrix. Biofilm cells are a major problem in the context of chronic infections, because biofilm dwelling cells have increased antibiotic resistance compared to their planktonic counterparts. Investigations so far have mainly focused on the genetic and regulatory features driving biofilm formation. However, still lacking is a fundamental biophysical and biomechanical understanding of how bacteria, in time and space, build these dense three-dimensional structures. During this talk, I will discuss about our recently progress in using Vibrio cholerae as a model biofilm former to reveal the mechanical principles behind biofilm formation. I will first present a new methodology to image living, growing bacterial biofilms at single-cell resolution, and demonstrate how cell-cell adhesion and cell-surface adhesion balance each other to cause V. cholerae biofilms to transition from a two-dimensional branched morphology to an ordered three-dimensional cluster. Next, I will demonstrate how matrix production enables biofilm cells to establish an osmotic pressure differential between the biofilm and the external environment, and use this osmotic pressure to facilitate the biofilm expansion. Finally, I will present various mechanical instabilities that takes place when biofilms grow on soft tissue-like substrates. We also complemented these mechanical studies by genetic analyses and ecological competition experiments to decipher the biological consequences of the biomechanical phenomena observed in bacterial biofilms.