| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 600031 | Colloids and Surfaces B: Biointerfaces | 2013 | 8 Pages |
The aim of this study was to investigate the effects of surface characteristics of plain and plasma modified cellulose acetate (CA) membranes on the immobilization yield of β-galactosidases from Kluyveromyces lactis (KLG) and its galacto-oligosaccharide (GOS) yield, respectively. Low pressure plasma treatments involving oxygen plasma activation, plasma polymerization (PlsP) of ethylenediamine (EDA) and PlsP of 2-mercaptoethanol were used to modify plain CA membrane surfaces. KLG enzyme was immobilized onto plain and oxygen plasma treated membrane surfaces by simple adsorption. Oxygen plasma activation increased the hydrophylicity of CA membrane surfaces and it improved the immobilization yield of the enzyme by 42%. KLG enzyme was also immobilized onto CA membrane surfaces through amino groups created by PlsP of EDA via covalent binding. Plasma action at 60 W plasma power and 15 min. exposure time improved the amount of membrane bounded enzyme by 3.5-fold. The enrichment of the amount of amino groups via polyethyleneimine (PEI) addition enhanced this increase from 3.5-fold to 4.5-fold. Although high enzyme loading was achived (65–83%), both of the methods dramatically decreased the enzyme activity (11–12%) and GOS yield due to probably negative effects of active amino groups. KLG enzyme was more effectively immobilized onto thiolated CA membrane surface created by PlsP of 2-mercaptoethanol with high immobilization yield (70%) and especially high enzyme activity (46%). Immobilized enzymes on the CA membranes treated by PlsP were successively reutilized for 5–8 cycles at 25 °C and enzymatic derivatives retained approximately 75–80% of their initial activites at the end of the reactions.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► I provided detailed information about immobilization of β-galactosidase enzyme onto cellulose acetate membrane surfaces. ► I investigate the effects of plasma surface modifications to the surface characteristics of cellulose acetate membranes. ► Plasma surface modifications significantly change the immobilization yield and activity of the β-galactosidase enzyme. ► The combination of membrane separation and biocatalytic activity produce high yield of galacto-oligosaccharide.
