Speaker
Description
Bioclogging is a process that result from the separation of biological particles from a fluid by a membrane; it has many environmental and sanitary applications. It results in a reactive porous medium with emerging properties: cells are deformable, can proliferate, consume nutrients and oxygen, and die. These specific features affect the structure and behavior of the porous medium. The coupling between proliferation, clog growth, and nutrient consumption can lead to a nutrient-limited environment, altering the proliferation of the organisms [1]. Bioclogging can thus be used to study the dynamics of reactive porous media under environmental constraints. Our objective is to investigate the spatio-temporal features of cell proliferation within a yeast assembly perfused with nutrients at the microscopic scale.
The model organism is Saccharomyces cerevisiae. A quasi-2D microfluidic system was developed, in which yeast cells are retained by a pore and continuously perfused with culture medium [2]. Two distinct growth regimes are observed during clog formation, corresponding to different states of the clog. In the initial phase, clog growth is exponential, associated with uniform proliferation throughout the clog. After a few hours, the clog length evolves linearly with time. Two distinct regions emerge: one proliferative, the other quiescent – as demonstrated by biological marking. We are also able to quantify local proliferation rates within the clog using local displacements. These results highlight the coupling between bioreactive flow and proliferation: growth reduces the flow rate, which in turn reduces the proliferation rate.
A mathematical model has been developed to support the experimental observations. It relies on three key components: a Monod-type proliferation law dependent on nutrient concentration, an advection-diffusion-reaction nutrient transport equation, and a Darcy description of flow through the clog. These equations are coupled to capture the interplay between cell growth, nutrient depletion, and flow reduction. The model successfully reproduces the transition between the observed growth regimes, as well as the emergence of spatially differentiated zones within the clog.
| References | [1] Vulin et al., Growing Yeast into Cylindrical Colonies, Biophysical Journal, 106, 2214-2221 (2020) ; [2] Desclaux et al., Hydrodynamic resistance of a yeast clog, Physical Review Fluids, 9 (2024) |
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| Country | France |
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