title: Fed-batch synthesis of galacto-oligosaccharides with Aspergillus oryzae β-galactosidase using optimal control strategy.
abstract: Fed-batch synthesis of galacto-oligosaccharides (GOS) from lactose with β-galactosidase from Aspergillus oryzae was evaluated experimentally and reaction yield was maximized via optimal control technique. The optimal lactose and enzyme feed flow rate profiles were determined using a model for GOS synthesis previously reported by the authors. Experimentally it was found that fed-batch synthesis allowed an increase on the maximum total GOS concentration from 115 (batch synthesis) to 218 g L(-1) as consequence of the increase in total sugars concentration from 40 to 58% w/w. Such high concentration of total sugars was not attainable in batch operation because of the low solubility of lactose at the reaction temperature (40°C). Simulations predicted a GOS yield of 32.5 g g(-1) in fed-batch synthesis under optimal conditions, while experimentally the same yield as in batch synthesis was obtained (28 g g(-1) ). Besides, an enrichment of total oligosaccharides in GOS with a high polymerization degree (GOS-5 and GOS-6) was observed in the fed-batch synthesis. Experimental profiles for all sugars were similar to the ones predicted by simulation, which supports the use of this methodology for the optimization of GOS synthesis.
authors.affiliation: School of Biochemical Engineering, Pontificia Universidad Católica de Valparaíso, Avenida Brasil, 2147, Valparaíso, Chile.
authors.forename: Carlos
authors.initials: C
authors.lastname: Vera
authors.forename: Cecilia
authors.initials: C
authors.lastname: Guerrero
authors.forename: Andrés
authors.initials: A
authors.lastname: Illanes
authors.forename: Raúl
authors.initials: R
authors.lastname: Conejeros
mesh_terms: D001236:Aspergillus oryzae / Q000201:enzymology* / Q000378:metabolism*; D019149:Bioreactors / Q000382:microbiology; D003198:Computer Simulation; D005656:Fungal Proteins / Q000378:metabolism*; D005690:Galactose / Q000378:metabolism; D008954:Models, Biological; D009844:Oligosaccharides / Q000032:analysis / Q000378:metabolism*; D013696:Temperature; D001616:beta-Galactosidase / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D009844:Oligosaccharides; D001616:beta-Galactosidase; D005690:Galactose
keywords: Aspergillus oryzae; GOS; fed-batch enzymatic synthesis; galacto-oligosaccharides; prebiotics; β-galactosidase