Production of D-galactose using β-galactosidase and Saccharomyces cerevisiae entrapped in poly(vinylalcohol) hydrogel

D-Galactose was produced from lactose (200 g l(-1)) in the batch mode of a simultaneous saccharification and fermentation process (SSF). beta-Galactosidases (from Kluyveromyces lactis and Aspergillus oryzae) and yeasts were immobilized in poly(vinylalcohol) hydrogel lens-shaped capsules - LentiKats (R). After 20 repeated batch runs with entrapped K. lactis, beta-galactosidase and free Saccharomyces cerevisiae (10% v/v inoculum), galactose productivity decreased to 50% and 1.4 kg of galactose were prepared. Compared to this. just 20% decrease of galactose productivity and a 0.9 kg production of galactose were observed for the SSF process with beta-galactosidase from A. oryzae after 15 repeated batches under the same conditions. In the process of SSF with co-immobilized enzyme from K. lactis and S. cerevisiae, the galactose productivity increased from 3 g l(-1) h(-1) to 4.1 g l(-1) h(-1), which reduced the time of preparation of D-galactose. (C) 2009 Elsevier Ltd. All rights reserved.