The proposal research is directed at developing an extraction technique to recover proteins from an aqueous solution utilizing a temperature-sensitive microemulsion phase. The technique may be utilized as a primary recovery step for large-scale bioseparations. By utilizing liquid phase mass transfer, residence times for primary isolation can be minimized and protease action eliminated. Microemulsions possess several processing advantages over two-phase aqueous systems for such and extraction technique, including ease of phase disengagement (eliminating the need for capital- intensive centrifuges) and low viscosity materials (allowing for faster mass transfer). By utilizing a nonionic surfactant, an mild temperature increase can be utilized to recover the protein in a concentrated form instead of utilizing chemical addition as currently practiced for ionic surfactant reverse micellar systems. Nonionic temperature- sensitive microemulsions require the incorporation of an affinity ligand to obtain the high degree of specificity desired. A reversible inhibitor of a model enzyme, - galactosidase, will be chemically attached to the ethylene oxide adduct of the nonionic surfactant employed to form the temperature-sensitive microemulsion. The partitioning of - galactosidase into the formulated microemulsion will be investigated as a function of temperature. Solubilization of the enzyme is expected to occur at a low temperature (4 C), while demulsification and enzyme recovery will occur at a higher temperature (35 C) which is well below the denaturation temperature for -galactosidase (50% denaturation occurs at 57 C). This microemulsion system will then be utilized to study the processing advantages of a temperature-sensitive microemulsion on a bench-scale continuous separation unit.
