Enhanced thermostability of the Immobilized Thermoalkalophilic Esterase onto Magnetic-Cornstarch Nanoparticle.

Öz, Yasin; Sürmeli, Yusuf; Şanlı-Mohamed, Gülşah

The immobilization of the biocatalysts onto magnetic nanoparticles (MNPs) has been extensively applied since the external magnetic field facilitates the enzyme recovery from the reaction mixture. In the present study, glutaraldehyde-modified magnetite-cornstarch nanoparticles (MCNs) were successfully synthesized, elaborately characterized by ZetaSizer and surface-enhanced raman spectroscopy (SERS), and used for the immobilization of a thermoalkalophilic esterase from Geobacillus sp. The optimal immobilization conditions were obtained at 65°C, 2:3 molar ratios of Fe2+ :Fe3+ and 1 g cornstarch resulted in approximately 90 nm magnetic particles in size. Also, immobilization yield and immobilization efficiency of the esterase were found as 74% and 82%, respectively. Scanning Electron Microscopy (SEM) micrographs showed that MCNs were uniform, spherical in shape, and well dispersed and esterase immobilized MCNs displayed similar morphology as free MCNs. The maximum activity of free and immobilized esterase was obtained at 65°C and pH 9. Immobilization onto glutaraldehyde-modified MCNs significantly enhanced the esterase thermostability. Additionally, the immobilized esterase kept its residual activity of 75% after three sequential cycles, suggesting that it has favorable operational stability. A thermoalkalophilic esterase from Geobacillus sp. has been immobilized on glutaraldehyde-modified magnetite-cornstarch nanoparticles (MCNs) and characterized elaborately for the first time. The optimal immobilization conditions were obtained at 65°C, 2:3 molar ratios of Fe2+ :Fe3+ and 1 g cornstarch resulted in approximately 90 nm magnetic particles in size. Immobilization yield and entrapment efficiency of the esterase were found as 74% and 82%, respectively. The maximum activity of free and immobilized esterase was obtained at 65°C and pH 9. Immobilization significantly enhanced the esterase thermostability. The immobilized esterase kept its residual activity of 75% after three sequential cycles, suggesting that it has favorable operational stability. This article is protected by copyright. All rights reserved.