Reverse micellar extraction and precipitation of lysozyme using sodium di(2-ethylhexyl) sulfosuccinate

Sodium di(2-ethylhexyl) sulfosuccinate, referred to as Aerosol-OT or AOT, was used to remove lysozyme from an aqueous phase via reverse micellar extraction and precipitation method. For both methods, when the surfactant was in excess, a complete removal of lysozyme from the aqueous phase was obtained at the values of pH below the pI of lysozyme. However, for the reverse micellar method, a solubilization limit of lysozyme in the organic phase was observed, and a white precipitate was formed at the aqueous-organic interface. This observation suggested using AOT directly as a precipitating ligand. The lysozyme precipitated with AOT was fully recovered, with its original enzymatic activity, using acetone as a recovery solvent. A mechanism is suggested to explain the solubilization of lysozyme in an AOT reverse micellar system. It is shown that a direct precipitation method can be used with advantage instead of using the reverse micellar extraction method to recover lysozyme from an aqueous phase.