Control of Substrate Inhibited Steady States for Model Validation

Abstract

Substrate inhibition is an important situation in the degradation of pollutants and xenobiotics. Short term adaptation of the cells and lacking model validation in batch experiments will lead to erroneous results making experiments in continuous cultivation necessary. Resulting unstable reactor dynamics can be stabilized employing model predictive control. Two examples are shown, namely degradation of phenol and degradation of quinoline. In the first case, a precise determination of substrate uptake kinetics including substrate inhibition is obtained. In the latter case, intermediates can diffuse through the cell membrane and accumulate in the medium. This makes intracellular metabolite concentrations observable without expensive analytics. This interesting feature is accompanied by increased problems in model validation. Model discrimination and parameter estimation are shown to be possible only under substrate inhibited steady state conditions. Experimental and modeling results are shown.