Sugar evolution by microbial hydrolysis of corncob and sugarcane bagasse : effect of steam-explosion pretreatment

Abstract

Currently, bioethanol is a promising alternative fuel. It can be easily produced by the conversion of lignocellulosic materials into reducing sugars and further fermented into ethanol. The major lignocellulosic materials, like sugarcane bagasse and corncob residue, have been studied. Corncob consists of 43.35% cellulose, 31.86% hemicellulose, 18.25% lignin, and 6.54% ash, while sugarcane bagasse consists of 41.96% cellulose, 25.96% hemicellulose. and 12.43 % lignin. The aim of this research was to study effects of steam-explosion pretreatment on the glucose evolution from corncob and sugarcane bagasse by microbial hydrolysis of cellulase-producing bacteria, Bacillulus subtilis, isolated from Thai higher termites, Microcerotermes sp., in an aerobic batch reactor. H2O and H2SO4 impregnated biomass was steam-exploded by high temperature (120 ℃) for 1, 2, and 3 h in order to determine the optimum condition for fermentable sugar production. The optimum pretreatment condition is at 1 h for the H2O-impregnated sugarcane bagasse, while the H2O-impregnated corncob is at 2 h. The maximum glucose concentration at the optimum condition, for H20-impregnated steam explosion pretreatment of sugarcane bagasse and corncob, are 0.369 g/L at 6 h and 0.262 g/L at 5 h, respectively. Furthermore, the optimum pretreatment condition was at 1 h for the H2SO4- impregnated sugarcane bagasse and corncob. The maximum glucose concentration at the optimum condition, for H2SO4-impregnated steam explosion pretreatment of sugarcane bagasse and corncob are 0.6 g/L and 0.265 g/L, respectively.