Designing biodegradable aqueous biphasic systems for the selective separation of enzymes

Abstract

In this work, the salting-out strength of reline eutectic mixture in aqueous solution of the non-ionic surfactant Triton X-102 has been demonstrated at temperatures between 298.15 and 323.15 K as a preliminary step to be employed in downstream operations of a biotechnological process. The phase diagrams data of reline-based Aqueous Two Phase Systems (ATPS) have been correlated using empirical models based on exponential and polynomial equations. The tie-lines have been empirically ascertained through physical properties characterization and Othmer-Tobias equation was proposed to correlate those data. After having studied the effect of the proposed reline eutectic mixture on two model enzymes (protease and lipase), the performance of this ATPS for selectively separating them was evaluated for three different feed compositions on the same tie-line, demonstrating their pertinence to segregate the lipase to one of the phases (yield about 95 %) and the protease to the other phase (yield about 98 %). These promising results are interesting for application in biotechnological reactions where proteases have been proved to be deleterious for lipases activity, as the biocompatibility of the proposed platform does not involve drastic negative effects on any of the enzymes.