Abstract

High-gradient magnetic separation based processing is demonstrated for the semi-continuous multicycle re-use of a lipase immobilised on magnetic microparticles. The lipase of Candida antarctica A-type (CALA) was immobilised on polyvinyl alcohol coated magnetic particles (1-2 mu m diameter) with epoxy functionalisation. The immobilised CALA was used to hydrolyse a model oil-water 2-phase-system composed of a phosphate buffer with tributyrin at up to 31 scale. The immobilised enzyme was subsequently recovered in a magnetic filter using high-gradient magnetic separation and reapplied in repeated cycles of hydrolysis and recovery.

Two different temperatures of 30 and 50 degrees C, tributyrin concentrations (0.12 and 35 g l(-1)) and reaction times were tested. In each case the reaction was followed by pH titration using NaOH, as well as by HPLC analysis. Consecutive cycles were conducted for each reaction condition and in total the immobilised CALA was subjected to 20 recovery and re-use cycles, after which similar to 14% of the initial specific activity still remained.