Catalytic properties of membrane-bound Mucor lipase immobilized in a hydrophilic carrier

Abstract

Membrane-bound Mucor circinelloides and Mucor racemosus lipases (mycelium treated with acetone and dried) were entrapped in cryogel beads obtained from polyvinyl alcohol (PVA) by a freezing–thawing method in two-phase system. Due to the porosity of PVA-cryogels, high molecular-weight substances can penetrate beads of the biocatalyst [1]. The biocatalyst was applied for various hydrolysis and synthesis reactions. The immobilization in cryoPVA-gel stabilized the enzyme [2] and ensured high mechanical and chemical stability of the biocatalyst, which could be used many times for p-nitrophenyl acetate (p-NPA), p-nitrophenyl palmitate (p-NPP) and triacyloglycerols hydrolysis. The biocatalyst can be also applied for esters synthesis in non-aqueous milieu, but before the reaction it has to be dried with acetone. The dynamics of four esters (butyl and propyl oleates, and caprylates) synthesis in petroleum ether was examined. The efficiency of butyl oleate synthesis was 99%. The yield of the ester synthesis varied within the initial 4h of the reaction. The phenomenon resulted from the cyclic accumulation of the water released upon ester synthesis, in the hydrophilic PVA-gel, that favored either ester synthesis or hydrolysis. The lipases entrapped in the dried cryo-PVA beads showed enhanced thermal and operational stability during repeated uses in ester synthesis in the non-aqueous system.