Microorganisms in heterogeneous flows: integrating from the cellular to the system-scale and from fundamental physics to applications


Yohan Davit, Institut de Mécanique des Fluides de Toulouse (IMFT), Université de Toulouse, CNRS, INPT, UPS, Toulouse, France
Pietro de Anna, Institute of Earth Sciences, University of Lausanne
Brian D. Wood, School of Chemical, Biological and Environmental Engineering, Oregon State University, Corvallis, USA


The majority of biomass on Earth is composed of bacteria and a large part of them live in the subsurface, where they are living agents of a complex network of processes: they contribute in catalyzing chemical reactions, enhancing their kinetic rates, or degrading / producing pollutants. Such small scale processes have a major impact on the fate of water resources at large scale: this include chemical engineering systems, bioreactors, water distribution systems, the hyporheic zone, stream beds, the vadose zone, subsurface remediation environments, soils, and deep reservoirs. In such environments, biochemical activities are often observed in localized “hot spots” identified with interfaces characterized by gradients in microbial communities, concentrations of chemical species (i.e., nutrients, oxygen, and metals) and heterogeneous fluid flows. The complexity rising from the coupling of these small-scale biological chemical and physical processes implies that predictions based on rates measured in well-mixed conditions differ by orders of magnitudes from observations in the field. This suggest a more mechanistic understanding of these processes, such as the one that can be obtained by small-scale analysis, is an imperative next step.

The goal of this cross-disciplinary session is to gather researchers with interest in the mechanisms that control the occurrence, distribution and ecology of microorganisms in heterogeneous and porous environments at the microorganism or population scale. Possible methods of interest include a diverse array of approaches, including theoretical (e.g., game theory, homogenization, metacommunity analyses), experimental (e.g., microfluidics, population genetics, imaging methods such as x-ray microtomography), and numerical (e.g., individual-based models, hybrid modeling, computational fluid mechanics models, solid mechanics models). Although there have been many recent advances in the subject area, many of the fundamental mechanisms that control the occurrence, growth, transport, and ecology of microorganisms in heterogeneous porous materials are still unknown. Thus, we expect this to be a challenging area of research for the foreseeable future.


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