Dynamic modeling of Rhodospirillum rubrum PHA production triggered by redox stress during VFA photoheterotrophic assimilations

Abstract

Polyhydroxyalkanoates (PHA) represent an environmentally friendly alternative to petroleum based plastics for a broad range of applications from packaging to biomedical devices. In the prospect of an industrial PHA production, it is highly valuable to accurately control the incorporation of different repeating units into the polymer, to produce a polyester with specific material characteristics. In this study, we develop macroscopic dynamic models predicting the polymer production and composition when mixtures containing up to four volatile fatty acids (VFA) are used as substrates. These models successfully reproduce the sequential (and preferential) substrate consumption and polymer production/reconsumption patterns, experimentally observed during biomass growth, thanks to simple kinetic structures based on Monod and inhibition factors. These models can serve as a basis for numerical simulation and process analysis, as well as process intensification through model-based optimization and control.

Keywords: PHA production; Parameter estimation; Resource recovery; Rhodospirillum rubrum; Wastewater treatment.