Abstract: Inverse suspension combined with the sol-gel method was deployed to prepare a magnetic chitosan microspheres. The lipase was immobilized on magnetic chitosan microspheres with genipin as the cross-linking reagent. The optimum conditions and properties of immobilization enzyme were investigated. The maximal specific activity of 4.31 U/g was achieved when the crosslinking reaction was carried out at 55 ℃ for 8 h using 0.6 g/L genipin. The optimum pH, temperature and Km of the immobilized enzyme were 8, 25~35 ℃ and 0.26 mol/L, respectively. The immobilized lipase showed improved thermal stability and remained active in a broader pH range, compared with those of free lipase. Such immobilized lipase can be recycled via the magnetic separation for a certain extent.

Key words: Magnetic chitosan microspheres, genipin, immobilized enzyme