Extractive Bioconversions in Aqueous Two-Phase Systems

The incorporation of an extractive step as a means of product separation during bioprocesses has been demonstrated to be a feasible technology for improving reactor productivity and also for reducing downstream processing costs. Two-phase systems generated by mixing aqueous solutions of two different polymers, or a polymer and a salt in a certain range of proportions, provide a powerful method for separation of biomolecules by extraction. This extraction is based upon the surface properties of the molecule and the composition of the phase system. Aqueous two-phase systems are characterized by an extremely low interfacial tension. The application of aqueous two-phase systems offers certain advantages when designing an extractive bioconversion. The concept of combining extraction in an aqueous two-phase system with separation in ultrafiltration also protects the membrane from coming into contact with the particulate matter in the medium, thus increasing its operational life.