Enzyme supplementation as a strategy for enhancing the cellulose and hemicellulose conversion yields at high solids content of pretreated rice straw

An efficient strategy for the high-solids enzymatic hydrolysis of lignocellulosic biomass is crucial for producing a sugar-rich hydrolysate. In this sense, the effect of Viscozyme L supplementation at different loads (5 – 60 mg protein/g hemicellulose) of Cellic CTec2 on cellulose (GCY) and hemicellulose conversion yield (HCY) was evaluated, using 20 % w/v of pretreated rice straw in shake flasks. At optimum Viscozyme L load (15 mg protein/g hemicellulose), 87 and 66 % of GCY and HCY were achieved, respectively. Then, the release of sugars was further improved by using an anchor-type impeller reactor. The resulting hydrolysate, composed of (g/L): glucose (∼85), xylose (∼38), and arabinose (∼8), was finally fermented by Candida guilliermondii FTI 20037 yeast, showing high efficiency (96 %) and volumetric productivity (2.06 g/L/h) from glucose. Therefore, supplementation with commercially available enzymes in a non-conventional reactor improved the performance of high-solids enzymatic hydrolysis and could be a promising strategy for industrial applications.