Enzymatic hydrolysis of lignocellulose: SEC-MALLS analysis and reaction mechanism

Abstract

The measurement of molecular parameters, such as molecular weight and degrees of polymerisation, in lignocellulosic feedstock are critical during the hydrolysis process, because following the changes in these parameters can provide insight into the mechanism of hydrolysis. This work employs SEC-MALLS to monitor the changes in the absolute values of these parameters of lignocellulosic samples during enzymatic hydrolysis. The lignocellulosic samples were directly dissolved in 8.0% LiCl/DMAc without any change. The number- and weight-average molecular weights of the cellulose fraction decreased initially and increased slightly thereafter, indicating that a “layer-by-layer” mechanism is adapted for enzymatic hydrolysis of the cellulose fraction of lignocellulose. Similar changes in the molecular weights of the hemicellulose fraction indicates that hemicellulose and cellulose are always together in the recalcitrant substrates during enzymatic hydrolysis. Finally, the reaction mechanism of cellulase on lignocellulose was defined by SEC-MALLS analysis combining HPLC and XRD data.