Improved saccharification of pretreated lignocellulose by Clostridium thermocellum with the addition of surfactant, low loading of cellulose

Abstract Saccharification of lignocellulose is prerequisite for the biorefinery. Clostridium thermocellum is a promising candidate for the hydrolysis of lignocellulose. A study on the saccharification by Clostridium thermocellum combined with surfactant and cellulase addition was investigated. The reducing sugars content increased with increasing substrate loading in the fermentation of C. thermocllum with isooctyl alcohol polyoxyethylene ether (IAPE) addition. Based on IAPE addition, the glucose content of two-step saccharification was higher than that of the batch saccharification. Besides, the addition of IAPE and Triton X-100 had the same effect on saccharification. The saccharification performance was related to the substrate, especially the lignin content. For the fed-batch hydrolysis of 20 % (w/v) rice straw pretreated by hydrogen peroxide-acetic acid (HPAC), 66.9 g/L glucose and 19.5 g/L xylose were obtained by using C. thermocellum DSM 1313 and 1 FPU/g substrate cellulase with 0.1 % (w/v) IAPE addition, and the glucose and xylose yield reached 63.2 % and 37.4 % respectively.