Enzyme recovery by liquid-liquid extraction using reversed micelles

Abstract

The recovery of α-amylase by liquid-liquid extraction, using a reversed micellar phase to transport the enzyme from one aqueous phase to another, has been investigated. Reversed micelles are aggregates of surfactant molecules in an apolar solvent, surrounding an inner core of water. Reversed micelles of the cationic surfactant trioctylmethylammonium chloride were used to solubilize α-amylase in isooctane. A continuous forward and back extraction of the enzyme was performed in two mixer-settler units, with the reversed micellar phase circulating between the two units. During the forward extraction the conditions ( pH, ionic strength) favoured the transfer of α-amylase from the aqueous phase towards the reversed micellar phase. The reversed micellar phase containing the α-amylase was subsequently extracted with a second aqueous phase, which favoured the transfer of the enzyme towards the aqueous phase. In this way, the concentration of active α-amylase in the second aqueous phase was eight times that of the original solution. An enzyme activity loss of 30% occurred during the extraction procedure. The forward and back extraction could be described in terms of the data on the distribution coefficients and the mass transfer rate constants.