Enhanced stability of Kluyveromyces lactis β galactosidase immobilized on glutaraldehyde modified multiwalled carbon nanotubes

The present study demonstrates covalent immobilization of Kluyveromyces lactis 13 galactosidase on functionalized multi-walled carbon nanotubes (MWCNTs). Highly efficient surface modification of MWCNTs was achieved by glutaraldehyde for binding greater amount of enzyme. X-ray diffraction analysis and UV visible spectroscopy of MWCNTs showed them to be entirely dispersive in aqueous solution. Transmission electron microscopy showed that MWCNTs were of 20 rim size. Thermogravimetric analysis further revealed the stability of glutaraldehyde modified MWCNT as an ideal matrix for enzyme immobilization. The optimal pH for soluble and immobilized beta galactosidase was observed at pH 7.0 while the optimal operating temperatures were observed at 40 degrees C and 50 degrees C, respectively. Moreover, our findings demonstrated that beta galactosidase immobilized on surface functionalized MWCNTs retained greater biocatalytic activity at higher galactose concentration, and upon repeated uses as compared to enzyme in solution. (C) 2013 Elsevier B.V. All rights reserved.