Enhanced Enzymatic Saccharification of Wheat Flour Arabinoxylan and Barley Straw Using Recombinant Hemicellulases

Enzymatic hydrolysis of hemicelluloses in biomass feedstocks requires multiple enzymes for sacchari-fication to fermentable monosaccharides. Considering the high cost of enzymes, the need for enzymes in the cocktail for maximum saccharification can be minimized using a statistically significant experimental design. In the present study, response surface methodology was used to optimize the saccharification of wheat arabinoxylan and pretreatment of barley straw. A hemicellulase enzyme mixture consisting of recombinant xylanase (rPcXynC), arabinanase (rPcAra), and bifunctional β-xylosidase/L-arabinofuranosidase (rPcXyl) was used. A central composite design was used to evaluate and confirm the effectiveness and interactions of these enzymes along with reaction time. A 100% sacchari-fication of 1 g of wheat arabinoxylan was achieved using 21.85 U, 6.025 U, and 182 U of rPcXynC, rPcAra, and rPcXyl, respectively, for 11.46 h. Subsequently, using pretreated barley straw as a substrate, a maximum saccharification of 42% was achieved in 12 h using an enzyme cocktail of 25 U rPcXynC, 5 U rPcAra, and 200 U rPcXyl. The total hydrolysis of pretreated barley straw was increased to 1.71% by the addition of acetyl xylan esterase as a pretreatment factor followed by optimization of enzyme cocktail. The experimental values under the optimum conditions were consistent with the predicted values and a minimum cocktail was involved for a synergistic effect of the enzymes.