Investigation of dynamic changes of substrate features on enzymatic hydrolysis of lignocellulosic biomass

During enzymatic hydrolysis of lignocellulosic biomass, the retardance of reaction has been widely observed, which is attributed to enzyme activity loss and/or substrate reactivity reduction. A real lignocellulosic biomass, dilute acid pretreated switchgrass instead of pure cellulose was used in this research. A series of hydrolysis of partially hydrolyzed pretreated switchgrass were conducted to study the effect of the dynamic change of substrate properties on the enzymatic hydrolysis. The digestibility, enzyme adsorption characteristics, surface areas of cellulose and lignin in partially hydrolyzed switchgrass were determined and compared. A new method was used to quantify the strong negative correlation between lignin content and hydrolysis rate/yield, which indicates that the increasing lignin content caused significant inhibitory effect. The cellulose decomposition during hydrolysis resulted in decrease of accessible cellulose surface area, but cellulose crystallinity of substrate had only slight change, which coincided with more exposure of lignin and increase of lignin surface area. That led to more nonproductive adsorption of enzyme to lignin and reduced the amount of enzyme available for cellulose hydrolysis.