Should I stay or should I go? Spatio-temporal dynamics of Pseudomonas aeruginosa biofilms in microchannel flows

Massinissa Benbelkacem (1) , Gabriel Ramos , Fatima El Garah , Yara Abidine , Christine Roques , Yohan Davit

1 IMFT - Institut de mécanique des fluides de Toulouse

Flow plays a particularly important role in the development of bacterial colonies and biofilms: advection efficiently transports nutrients, biocides and molecular signals; flow sensing systems modulate the biological response at the cellular level; and hydrodynamic stresses remodel the biomass and induce detachment. Understanding the coupling mechanisms between biofilms and flow remains an important challenge at the interface between microbiology and mechanics. Here, we study the development of Pseudomonas aeruginosa in microchannel flows, from the initial adhesion to the formation of mature biofilms. Combining microfluidics with timelapse microscopy, we find that biofilm development features complex spatio-temporal dynamics. We demonstrate that nutrient limitation is the primary driver for the longitudinal distribution of biomass, while a competition between growth and detachment dominates the temporal dynamics. For a broad range of flow conditions, we show that the system never reaches a true steady-state, even after several days, but instead features large fluctuations that stem from successive cycles of sloughing and growth. We also show that detachment is accurately modeled as two separate components in a differential equation for biomass evolution: a continuous sink term describing smooth detachment and a jump stochastic process that captures catastrophic sloughing events. This behavior in microchannels generalizes previous observations in more complex systems, thus suggesting that oscillations due to competitions between growth and detachment are ubiquitous and play an important role in the development and spreading of biofilms in infections, environmental processes and engineering applications. Our approach further opens the way towards a new quantitative approach to a stochastic characterization of biofilm detachment and the different factors that affect this behavior.

Mots clés: Biofilm; Flow; Confined systems

Domaines: Biophysique [physics.bio-ph]

Massinissa Benbelkacem, Gabriel Ramos, Fatima El Garah, Yara Abidine, Christine Roques, et al.. Should I stay or should I go? Spatio-temporal dynamics of Pseudomonas aeruginosa biofilms in microchannel flows. 2024. ⟨hal-04525107⟩