This study aims to investigate the phenomena of bacterial aggregation using a deterministic dynamical model. In particular our study focuses on Pseudomonas extremaustralis 2E-UNGS, a bacteria that it is found in the highly contaminated Reconquista River in Buenos Aires, Argentina. It has the ability to form aggregates that exhibit emergent properties such as biosorption and biotransformation of metals. These qualities make it particularly relevant for the development of bioreactors used in bioremediation.  We develope an experimental study to obtain the growth of Pseudomonas extremaustralis 2E-UNGS by measuring optical density using two different concentrations of a culture medium. Self-aggragation kinetics is studied by means of brightfield microscopy imaging. From these experiments we obtain the size and morphological characteristics of the cell aggregates as a function of time.  To study the dynamics of aggregation we propose a numerical model based on a master equation developed to describe the deterministic dynamical evolution of aggregate densities. This master equation considers size-dependent aggregation and fragmentation processes, with parameters derived from our experimental data.  Comparing the numerical results and the experimental data of Pseudomonas extremaustralis 2E-UNGS, we contribute to the understanding of the mechanism of cell aggregation, phenomenon that it is a previous stage of biofilm formation.

1- Daniel, M. A., Gotting, A. S., Beraha, N., Malgaretti, P., Carusela, M. F., & Vullo, D. L. (2024). Combined theoretical and experimental approaches for bacterial aggregation studies towards the improvement of bioremediation processes. Clean Technologies and Environmental Policy. https://doi.org/10.1007/s10098-024-02947-3