Preparation and characterization of nanomagnetic cross‐linked cellulase aggregates for cellulose bioconversion

Abstract

AbstractBACKGROUNDCellulose as a renewable biomaterial has forced attention on the use of cellulose‐hydrolyzing enzymes for industrial bioconversion of lignocellulosic materials to glucose. This paper reports immobilization of cross‐linked cellulase aggregates (CLEA) on the amine‐functionalized Fe3O4@silica core‐shell magnetic nanoparticles (MNPs).RESULTSThe optimum pH of the cellulase cocktail upon immobilization (cellulase CLEA–MNP) shifted a little to the acidic side whereas the optimum temperature did not change significantly. The behavior of CMCase activity in the cellulase CLEA–MNP at pH and temperature values higher than the optimum was significantly different compared with free cellulase. Cellulase CLEA–MNP retained about 45% of its maximum activity at pH values higher than 4.8, while free cellulase lost its activity sharply. Immobilized cellulase in contrast to the free form retained about 65% of its maximum activity at 80°C. Cellulase CLEA–MNP had improved thermal stability at 65°C. Operational stability of the immobilized cellulase was also noticeable. After a sharp decrease during two cycles of CMC hydrolysis, cellulase CLEA–MNP retained 30% of its initial activity through six cycles of reuse.CONCLUSIONSimple separation of MNPs from reaction medium and durability of CLEA–MNP composite during repeated use may overcome the major bottleneck against comprehensive applications of cellulase enzymes in industry. © 2014 Society of Chemical Industry