초록
<P>A rational optimization for the synthesis of galacto-oligosaccharides (GOS) from lactose catalyzed by β-galactosidase from <I>Aspergillus aculeatus</I>, included in the commercial product Pectinex Ultra SP-L, has been performed by using experimental design and surface response methodology. This accurate tool optimized empirical production of the most desired high-GOS (tri-GOS and tetra-GOS) up to 16.4% under the following reaction conditions: 59 °C, 4 U/mL free enzyme concentration, pH 6.5, 250 g/L initial lactose concentration, and 20 h of reaction. The statistical analysis revealed temperature and initial lactose concentration as critical parameters. The successful immobilization of the enzyme on a glyoxyl-functionalized porous silica support slightly increased the yield toward high-GOS (17.6%), especially tri-GOS yield (15.3%), under the optimized reaction conditions as compared to the free enzyme. Furthermore, the promotion of the transgalactosylation reaction toward tri-GOS production increased 1.5-fold the productivity of high-GOS as compared to the free enzyme.</P><P><B>Graphic Abstract</B><BR><IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jafcau/2017/jafcau.2017.65.issue-8/acs.jafc.6b05431/production/images/medium/jf-2016-05431h_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jf6b05431'>ACS Electronic Supporting Info</A></P>