title: [Synthesis of galacto-oligosaccharides by immobilized Bacillus stearothermophilus].
abstract: Bacillus stearothermophilus was embedded in sodium alginate, chitosan, gelatin respectively and utilized for galacto-oligosaccharides (GOS) production. By comparing with each other in the enzyme recovery, optimal reaction conditions, yields of GOS and mechanical strength of the carriers, the gelatin was selected as better carrier for immobilization. pH, temperature, lactose concentration, lactose conversion and mass transfer resistance of carrier significantly influenced the Yield of GOS. The maximum yield of GOS was 31.2% in a stirred reactor with lactose concentration at 60%. It remained about 88% after 96 h (8 batches) reaction. A packed bed was employed for a continuous reaction at space velocity 0.09 h-1, where GOS yield and reactor productivity was 31.5% and 17.4% respectively. It lost about 20% of its original yield of GOS after 140 h reaction. Products were separated by active charcoal columm. The chemical structure of tetrasaccharide identified by 13C-NMR was beta-D-Gal-(1-->3)-D-Gal-(1-->6)-Dal-(1-->4)-D-Glu.
authors.affiliation: State Key Laboratory of Bioreactor Engineering, Institute of Biochemistry, East China University of Science and Technology, Shanghai 200237, China.
authors.forename: S
authors.initials: S
authors.lastname: Chen
authors.forename: D
authors.initials: D
authors.lastname: Wei
authors.forename: Z
authors.initials: Z
authors.lastname: Hu
mesh_terms: D000464:Alginates / Q000737:chemistry; D019149:Bioreactors; D018914:Cells, Immobilized; D002686:Chitin / Q000031:analogs & derivatives* / Q000737:chemistry; D048271:Chitosan; D005780:Gelatin / Q000737:chemistry; D001411:Geobacillus stearothermophilus / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007785:Lactose / Q000378:metabolism; D009844:Oligosaccharides / Q000096:biosynthesis* / Q000737:chemistry; D013696:Temperature
chemical_list: D000464:Alginates; D009844:Oligosaccharides; D002686:Chitin; D005780:Gelatin; D048271:Chitosan; D007785:Lactose