Immobilization of Kluyveromyces lactis β galactosidase on concanavalin A layered aluminium oxide nanoparticles-Its future aspects in biosensor applications

Several new types of carrier and technology have been implemented in the recent past to improve traditional enzyme immobilization which aims to enhance enzyme loading, activity and stability in order to decrease the cost of enzyme in industrial processes. Thus, the present study aimed to work out a simple and high yield procedure for the immobilization of Kluyveromyces lactis beta galactosidase on a bioaffinity support, concanavalin A layered Al2O3 nanoparticles (Con A layered Al2O3-NPs). Thermogravimetric analysis of bioaffinity support revealed 6% loss in weight at 600 degrees C whereas its thermal decomposition was observed at 350 degrees C by differential thermal analysis. No significant change was noticed in the band intensity of pUC19 plasmid upon its treatment with Con A layered Al2O3-NPs. Comet assay further exhibited negligible change in tail length of comet after treating the lymphocytes by bioaffinity matrix. Atomic force microscopy revealed large surface area of Con A layered Al2O3-NPs for binding higher amounts of enzyme. Moreover, Fourier transform-infrared spectroscopy confirmed binding of beta galactosidase on bioaffinity support by exhibiting broadening in peaks at 3220.61 cm(-1) and 3447.27 cm(-1). Soluble and immobilized beta galactosidase showed same pH-optima at pH 7.0. However, immobilized enzyme exhibited enhanced pH stability and broad spectrum temperature optimum than soluble beta galactosidase. Immobilized beta galactosidase was found to be highly stable against product inhibition by galactose and retained 85% activity after its sixth repeated use. (C) 2011 Elsevier B.V. All rights reserved.