Stabilization of an intracellular Mucor circinelloides lipase for application in non-aqueous media

Different methods for stabilization of Mucor circinelloides lipase, facilitating its application in organic solvents were tested. Lipase was either isolated from the mycelium and immobilized on solid carriers (derivatives of cellulose, diatomaceous earth, modified porous glass) or immobilized in situ in the mycelium pellets and stabilized. The immobilized enzyme preparations were used for synthesis of sucrose, glucose, butyl and propyl oleates and caprylates, carried out in petroleum and di-n-pentyl ethers. Immobilized preparations of either crude or purified lipase isolated from the mycelium were at least 4–6 times less effective in sucrose esters synthesis than mycelium-bound lipase preparations. Lipase preparation with the highest synthetic activity was obtained by cross-linking of M. circinelloides mycelium pellets with glutardialdehyde (operational stability in sucrose caprylate synthesis was 94% after 4 runs (24 h each), and caprylic acid conversion was 91–85%). The best method for production of mechanically durable biocatalyst, which efficiently catalyzed sucrose esters synthesis, was found to be entrapment of the mycelium-bound lipase in polyvinyl pyrrolidone-containing chitosan beads solidified with hexametapolyphosphate.