Continuous production of lactulose by immobilized thermostable ß-glycosidase from Pyrococcus furiosus
- Publication Type
- Journal contribution (peer reviewed)
- Authors
- Mayer, J.; Kranz, B.; Fischer, L.
- Year of publication
- 2010
- Published in
- Journal of Biotechnology
- Pubisher
- Elsevier
- DOI
- 10.1016/j.jbiotec.2009.12.017
A continuous enzymatic process for the production of the prebiotic disaccharide lactulose through transgalactosylation was developed using free and immobilized ß-glycosidase from Pyrococcus furiosus. The hyperthermostable ß-glycosidase (CelB) was immobilized onto an anion-exchange resin (Amberlite IRA-93) or onto Eupergit® C with immobilization yields of 72% and 83%, respectively. The immobilized biocatalysts demonstrated specific activities of 920 nkat g-1 dry carrier and 1500 nkat g-1 dry carrier at 75 °C with p-nitrophenyl-ß-d-galactopyranoside as substrate. Continuous biotransformations in packedbed reactors using carrier bound CelB and in an enzyme membrane reactor using free CelB were carried out at 75 °C. Maximum lactulose yields of 43% related to the initial lactose concentration were reached with the carrier bound CelB preparations. The corresponding productivities were 52 g lactulose l-1 h-1 (Amberlite IRA-93) and 15 g lactulose l-1 h-1 (Eupergit® C), respectively. The free enzyme tested in an enzyme membrane reactor showed a product yield of 41% and a productivity of 12 g lactulose l-1 h-1 in the first day. While both carrier bound CelB preparations were 100% stable for at least 14 days, the half-life of the free CelB in the enzyme membrane reactor was only about 1.5 days.