Rahman_2016_Int.J.Biol.Macromol_87_488

A novel esterase, EstH was cloned, purified and characterized from the marine bacterium Zunongwangia sp. The purified EstH showed optimum activity at 30 degrees C and pH 8.5 with approximately 50% of original activity at 0 degrees C. EstH was stable in high salt conditions (0-4.5M NaCl). To improve the characteristics and explore the possibilities for application, a new immobilization matrix, Fe3O4 approximately cellulose nano-composite, was prepared and was characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Interestingly the optimal temperature of immobilized EstH elevated to 35 degrees C. Compared to its free form, immobilized EstH showed better temperature stability (48.5% compared to 22.40% at 50 degrees C after 30min), prolonged half-life (32h compared to 18h), higher storage stability ( approximately 71% activity compared to approximately 40% after 50days of storage), improved pH tolerance ( approximately 73% activity at pH 4 and 10), and, more importantly, reusability ( approximately 50% activity after 8 repetitive cycles of usage). Enzyme kinetics showed an increase in the Vmax (from 35.76 to 51.14muM/min) and Kcat (from 365s-1 to 520s-1) after immobilization. The superior catalytic properties of immobilized EstH suggest its great potential in biotechnology and industrial processes.