title: Stabilities of immobilized beta-galactosidase of Aspergillus sp. AF for the optimal production of galactooligosaccharides from lactose.
abstract: Beta-galactosidase of Aspergillus sp. AF crude homogenate was immobilized in Ca-alginate gel beads and used for the production of galactooligosaccharides (GOS) from lactose. Optimum pH and temperature, thermal and storage stability of the enzyme activity were investigated and compared with those of the free enzyme. The study on the improvement of mechanical strength of the alginate beads was carried out through various methods, which demonstrates that the hardening process, where the alginate beads were treated with 0.225 M CaCl(2) solution after three batches to compensate the lost of calcium in the beads, provided a high mechanical stability for repeated use in large-scale production. The experiment results show that GOS yield increased with the increase of lactose concentration, and also increased with excessive addition of lactose (exceeding its solubility) at the beginning of the reaction. The immobilization of beta-galactosidase of Aspergillus sp. AF crude homogenate is cheap in processing cost and easy to carry out, and the immobilized enzyme possesses high performance for industrial application.
authors.affiliation: College of Chemistry and Biology, Yantai University, Yantai, Shandong Province, PR China.
authors.forename: Yongmei
authors.initials: Y
authors.lastname: Feng
authors.forename: Xiulian
authors.initials: X
authors.lastname: Chang
authors.forename: Wenhua
authors.initials: W
authors.lastname: Wang
authors.forename: Runyu
authors.initials: R
authors.lastname: Ma
mesh_terms: D000464:Alginates; D001230:Aspergillus / Q000201:enzymology*; D002122:Calcium Chloride / Q000737:chemistry / Q000378:metabolism; D045424:Complex Mixtures; D004795:Enzyme Stability; D004800:Enzymes, Immobilized / Q000378:metabolism*; D005656:Fungal Proteins / Q000378:metabolism*; D020723:Glucuronic Acid; D006603:Hexuronic Acids; D006863:Hydrogen-Ion Concentration; D007218:Industrial Microbiology / Q000379:methods; D007785:Lactose / Q000737:chemistry / Q000378:metabolism; D008863:Microspheres; D025942:Oligosaccharides, Branched-Chain / Q000737:chemistry / Q000378:metabolism; D013696:Temperature; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D000464:Alginates; D045424:Complex Mixtures; D004800:Enzymes, Immobilized; D005656:Fungal Proteins; D006603:Hexuronic Acids; D025942:Oligosaccharides, Branched-Chain; D020723:Glucuronic Acid; D001616:beta-Galactosidase; D007785:Lactose; D002122:Calcium Chloride