Combinatorial pretreatments of reed straw using liquid hot water and lactic acid for fermentable sugar production

• Reeds was treated by liquid hot water and lactic acid (LHW-LA). • Enzymatic digestibility of glucan reached 80.62% using LHW-LA pretreatment. • Total sugar yield reached 39.19 g/100 g reeds. A green combinatorial pretreatment using liquid hot water (LHW) and lactic acid (LA) was used to treat reed straw for effective lignocellulose digestibility and xylose recovery. The reeds were first treated with LHW at 180 °C for 60 min, followed by LA treatment at 170 °C for 45 min. Using 37.5 g/L lactic acid, the lignocellulose digestibility was 80.6 % and glucose yield was 56.0 %, which was much higher than that for one-step LHW pretreatment (the lignocellulose digestibility was 27.3 % and the glucose yield was 26.3 %). These data demonstrated that LHW-LA pretreatment increased lignocellulose digestibility and glucose yield by 1.95-fold and 1.13-fold, respectively. The highest total sugar yielded 39.2 g/100 g -substrate . The results revealed that LHW-LA pretreatment removed most hemicellulose and partial lignin from the reed straw and prompted cellulase binding to reed cellulose, which enhanced lignocellulose enzymatic saccharification. The high fermentable glucose yielded from the combinatorial pretreatment as presented in this study highlighted the great potential of our pretreatment technology to be applied in the biorefinery, which could lay down the cost and sustainability of current biorefinery industry.