title: Production of Galactooligosaccharides Using β-Galactosidase Immobilized on Chitosan-Coated Magnetic Nanoparticles with Tris(hydroxymethyl)phosphine as an Optional Coupling Agent.
abstract: β-Galactosidase was immobilized on chitosan-coated magnetic Fe3O4 nanoparticles and was used to produce galactooligosaccharides (GOS) from lactose. Immobilized enzyme was prepared with or without the coupling agent, tris(hydroxymethyl)phosphine (THP). The two immobilized systems and the free enzyme achieved their maximum activity at pH 6.0 with an optimal temperature of 50 °C. The immobilized enzymes showed higher activities at a wider range of temperatures and pH. Furthermore, the immobilized enzyme coupled with THP showed higher thermal stability than that without THP. However, activity retention of batchwise reactions was similar for both immobilized systems. All the three enzyme systems produced GOS compound with similar concentration profiles, with a maximum GOS yield of 50.5% from 36% (w · v(-1)) lactose on a dry weight basis. The chitosan-coated magnetic Fe3O4 nanoparticles can be regenerated using a desorption/re-adsorption process described in this study.
authors.affiliation: Department of Bioengineering, Tatung University, Taipei 104, Taiwan. monica94707@yahoo.com.tw.
authors.forename: Su-Ching
authors.initials: SC
authors.lastname: Chen
authors.affiliation: Department of Bioengineering, Tatung University, Taipei 104, Taiwan. duan@ttu.edu.tw.
authors.forename: Kow-Jen
authors.initials: KJ
authors.lastname: Duan
mesh_terms: D002614:Chelating Agents / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry*; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000737:chemistry / Q000378:metabolism*; D052203:Ferrosoferric Oxide / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000737:chemistry; D058185:Magnetite Nanoparticles / Q000737:chemistry; D009844:Oligosaccharides / Q000138:chemical synthesis*; D010720:Phosphines / Q000737:chemistry*; D013696:Temperature; D001616:beta-Galactosidase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D002614:Chelating Agents; D004800:Enzymes, Immobilized; D058185:Magnetite Nanoparticles; D009844:Oligosaccharides; D010720:Phosphines; D048271:Chitosan; D001616:beta-Galactosidase; D007785:Lactose; D052203:Ferrosoferric Oxide; C505069:tris(hydroxymethyl)phosphine
keywords: Fe3O4 nanoparticles; THP; chitosan; enzyme immobilization; galactooligosaccharides; β-galactosidase