Synergistic Effect of Xylanase and Laccase on Structural Features of Energy Cane

Xylanase and laccase are now used more frequently in biomass biorefinery. Different operational conditions of the two enzymes reflect their limitations for enzyme cocktails. Xylanase and laccase bleaching efficiencies were studied to reveal evidence of their synergistic action on energy cane (EC) structural features. Temperature and pH of both enzymes were optimized to a one-step treatment of mixing enzymes after alkaline pretreatment. Results showed that a single pretreatment of 50 Ug-1 xylanase and 100 Ug-1 laccase significantly enhanced the whiteness index of pretreated fibers by 85%. Whiteness index increased to 95% when biobleaching synergistic xylanase/laccase treatment was applied. Synergistic xylanase/laccase-treated fibers showed 70% xylan removal, with enhanced crystallinity index at 59% compared to single xylanase and laccase-treated fibers. Synergistic xylanase/laccase treatment increased the specific surface area (2.8 m2g-1) and surface roughness (81.83 mu m) of the fibers, indicating partial xylan hydrolysis and lignin depolymerization. NMR spectroscopy exhibited bond cleavage of lignin-xylan and lignin inter-unit linkages due to enzyme synergistic actions. Results increase the understanding of synergistic action mechanisms between xylanase and laccase to improve biobleaching efficiency and can be implemented to enhance biorefinery production of various lignocellulosic biomass.