Effects of stress in the growth of microbial biofilms
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Date
2023
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Abstract
In active matter physics, bacteria are considered active agents that grow and reproduce by division. Some bacterial strains attach to surfaces forming biofilms which exhibit complex spatial behavior, governed by the internal and external physical interactions and many biological factors. Studies have been made about the biomechanical interactions that arise in such systems, but due to the complexity of the biological mechanisms, few conclusions about the dynamics of growth and underlying physics have been drawn. In the present work, we propose a simplified two dimensional biophysical model to reduce to a minimum the number of factors that affect dynamics of the system. Using numerical methods, we explore the parameter dependence of our model, applying different boundary conditions to our numerical simulations. Internal stresses and velocities within the system show an exponential profile that defines zones of buckling and a steady front that propagates the biofilm towards unoccupied regions. By taking averages over ensembles of cells, we create a continuous description of the system and compare the continuous theory to the dynamics given by the numerical simulations. We conclude that the modelled biofilm dynamics, stresses and growth agree to the theoretical results, and the growing front presents a characteristic length defined by the interplay between dynamical viscosity and cell stiffness.
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Tesis (Master in Theoretical Physics)--Pontificia Universidad Católica de Chile, 2023