Effects of monovalent cations (Na+ and K+) on galacto-oligosaccharides production during lactose hydrolysis by kluyveromyces lactis β-galactosidase
The influence of cations, Na+ and K+ on the oligosaccharides produced in the process of transglycosylation during the hydrolysis of lactose using β-galactosidase from Kluyveromyces (K.) lactis has been investigated. The enzyme exhibited higher hydrolytic activity in the presence of K+ than in that of Na+ regardless of the anion present (acetate or phosphate), thus 96% of lactose was hydrolyzed after 3h of reaction. Formation of di- and tri-saccharides also proceeded faster in presence of K+ than of Na+, however, the highest levels were reached in presence of Na+. Transgalactosylation was favoured at high concentrations of sodium buffer and, on the contrary, hydrolysis of both lactose and oligosaccharides was favoured at low salt concentrations. After 48h of reaction in 1M sodium acetate buffer a yield of 39.5% of galactooligosaccharides (GOS) was achieved (disaccharides 18.4% and trisaccharides 21.1%). The study of influence of Mg 2+ revealed that a concentration of 1 mM was necessary to obtain a 90% hydrolysis of lactose and a 16% of disaccharides formation after 8h of reaction; however, a maximum yield of trisaccharides of 19% was attained using the highest concentration of Mg 2+ (2 mM). These results could be applied to improve the GOS formation by β-galactosidase from K. lactis.
| Main Authors: | , , |
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| Format: | artículo biblioteca |
| Published: |
AVA Agrar-Verlag Allgäu
2012
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| Online Access: | http://hdl.handle.net/10261/101296 http://dx.doi.org/10.13039/501100004837 http://dx.doi.org/10.13039/100012818 |
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