Structured cell simulator coupled with a fluidized bed bioreactor model to predict the adaptive mercury uptake by E. coli cells

• An extended bioreactor model is proposed for the mercury uptake by immobilized E. coli cells.
• A three-phase bioreactor unstructured model is coupled to a structured cell dynamic simulator.
• The model predicts the response of the involved genetic regulatory circuit (GRC) to perturbations.
• The model predicts the bacteria adaptation to environmental changes through the involved mer-GRC.
• Model predictions are in agreement with the measured data using cloned cells with mer-plasmids.

A bi-level model is proposed by coupling a three-phase fluidized bioreactor (TPFB), used for mercury uptake from wastewaters by immobilized Escherichia coli cells, with a cellular simulator of the genetic regulatory circuit (GRC) controlling the mercuric ion reduction in the cytosol. While keeping a reasonable agreement with the experimental data from literature (free cell cultures with/without cell membrane permeabilization), the structured model advantages are coming from the prediction detailing degree [simulated 26 + 3 (cell + bulk) vs. 3 (bulk) variable dynamics] covering a wide range of input Hg2+ loads (0–100 mg L−1), and cloned E. coli cells with various amounts of mer-plasmids (3–140 nM). The model offers the possibility to predict the inner cell mercury reduction rate (different from the apparent rate observed in the bioreactor), the bacteria metabolism adaptation to environmental changes over several cell cycles, and the effect of cloning cells to modify their behaviour under stationary or perturbed conditions.

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