The Application of Polymers in Bioprocessing: Using First Principles Thermodynamic Methods to Predict Solute-Polymer Affinity in Partitioning Bioreactors

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Microorganisms continue to be effectively utilized to achieve two useful purposes: the biotreatment of toxic organic wastes, and the bioproduction of valuable products (e.g. biofuels, pharmaceuticals) from renewable feedstocks. Accordingly, the theme of my proposed research encompasses environmental engineering and biotechnology. Regardless of the application, the effective operation of bioprocesses is invariably constrained by toxicity to the microbes: high concentrations of toxic contaminants are in themselves toxic to the microbes responsible for their destruction, and, the desire to generate high concentrations of products in bioprocesses also leads to product toxicity to the cells. We have developed a technology platform, Two-Phase Partitioning Bioreactors (TPPBs), in which a water-immiscible material (phase) is added to the cell-containing aqueous phase to selectively partition toxic molecules either to the microorganisms in bioremediation applications, or away from the microbes in bioproduction systems to eliminate such toxicity. Research Groups in more than 20 countries around the world are now using our TPPB technology platform. Our recent NSERC DG-funded research was able to show that inexpensive polymer (plastic) beads can replace immiscible liquid solvents as the sequestering phase in TPPBs; however all of our applications involved hydrophobic (water insoluble) target compounds, and polymers were selected by trial-and-error. Many target toxic contaminants, and important bioroducts, however, are highly water soluble, and we need to be able to identify effective polymers for such TPPB applications. The objective of the proposed research is: to use best-available thermodynamic principles to predict which polymers have affinity for such target molecules; to create a universal guide for polymer selection using such a fundamental approach, and, to demonstrate the effectiveness of this predictive approach in important environmental and biotechnology TPPB applications. We are the world leaders in the creation and exploitation of the TPPB technology platform, and publish extensively on it though graduate student research. The proposed DG work will consolidate and expand this leadership position in sustainable technologies.