Magnetic cross-linked enzyme aggregates (CLEAs) for carrier free immobilization of lignocellulolytic enzymes

The enzymatic conversion of lignocellulosic biomass into biofuels has been identified as an excellent strategy to generate clean energy from wastes such as agricultural residues. However, the current process is cost-intensive. Furthermore, an effective immobilization approach to reuse enzymes in this process has been a major challenge. Our present study introduces the concept and application of novel magnetic cross-linked enzyme aggregates (mag-CLEAs). Both mag-CLEAs and calcium-mag-CLEAs (Ca-mag-CLEAs) exhibited a 1.35 fold higher xylanase activity compared to the free enzyme and retained more than 80.0% and 90.0% activity, respectively, after 136 h of incubation at 50 degrees C, compared to 50% activity retained by CLEAs alone. A 7.4 and 9.0 fold higher sugar release, from lime-pretreated and NH4OH pre-treated sugar bagasse, respectively, was achieved with Ca-mag-CLEAs compared to the free enzymes. This study therefore promotes the successful application of mag-CLEAs and Ca-mag-CLEAs as carrier free immobilized enzymes for the effective hydrolysis of lignocellulosic biomass and associated biofuel feedstocks. This approach also facilitates greater enzyme stability and reuse, and allows for greater process control.