Saccharification of a Potential Bioenergy Crop, Phragmites australis (Common Reed), by Lignocellulose Fractionation Followed by Enzymatic Hydrolysis at Decreased Cellulase Loadings

Cost-effective biological saccharification of nonfood lignocellulosic biomass is vital to the establishment of a carbohydrate economy. Phragmites australis (common reed) is regarded as an invasive perennial weed with a productivity of up to 18-28 tons of dry weight per acre per year. We applied the cellulose solvent- and organic solvent-based lignocellulose fractionation (COSLIF) to the stems and leaves of Phragmites and optimized the pretreatment conditions (e.g., temperature, reaction time, and biomass moisture content) through response surface methodology (RSM). The optimal pretreatment conditions were 85% (w/v) H3PO4, 50 degrees C, and 60 min, regardless of the biomass moisture contents from 5-15% (w/w). Glucan digestibility of the COSLIF-pretreated common reed was 90% at hour 24 at a low cellulase loading (5 filter paper units and 10 beta-glucosidase units per gram of glucan). Under these conditions, the overall sugar yields were 88% for glucose and 71% for xylose, respectively. Cellulose accessibility to cellulase (CAC) was increased 93.6-fold from 0.14 +/- 0.035 to 13.1 +/- 1.1 m(2) per gram of biomass with the COSLIF pretreatment. Results showed that cellulase concentrations could be reduced by 3-fold with only a slight reduction in sugar yield. This study suggested that Phragmites could be used as a carbon-neutral bioenergy feedstock, while its harvesting could help control its invasive growth and decrease nutrient pollution in adjacent waterways.