Cellulolytic enzyme interaction with lignocellulose. Insight to factors limiting enzymatic hydrolysis

Conference poster, 2013

Liberation of fermentable soluble sugars from lignocellulosic biomass during the course of enzymatic hydrolysis is the major obstacle to large-scale implementation of biorefineries due to high cost of enzymes. Enzymatic hydrolysis of lignocellulosic biomass is often incomplete and, therefore, it is of great importance to understand the limitations of the process. Among the limitations of enzymatic hydrolysis, structural properties of lignocellulose have an effect of enzymatic hydrolysis efficiency. Currently, there is a lack of direct methods for visualization and quantification of spatial polymer distribution in lignocellulosic biomass and monitoring of interactions between cellulose degrading enzymes and the substrate. The focus of the work was (i) structural characterization of lignocellulose during the course of hydrolysis and (ii) to provide a more detailed understanding of cellulolytic enzyme interaction with lignocellulose. The overall aim was to understand the limitations in enzymatic hydrolysis of lignocellulosic biomass. Enzymatic hydrolysis was studied on industrial-like lignocellulosic and cellulosic substrates, resulting from alkaline pulping and steam explosion of spruce. Enzymatic hydrolysis of lignocellulosic substrates was compared to enzymatic hydrolysis of model cellulosic substrates. Enzymatic hydrolysis of the substrates was performed with commercial enzyme mixture Celluclast 1.5 L and also with designed enzyme mixtures, consisting of mono-component enzymes. The structural properties of the substrates during an incrementing time of hydrolysis were analyzed by solid-state Nuclear Magnetic Resonance (NMR) spectroscopy, Coherent Anti-Strokes Raman Scattering (CARS) and Second Harmonic Generation (SHG) microscopy. Hydrolysis products were verified by High Performance Anion Exchange Chromatography with Pulsed Amperometric Detection (HPAEC-PAD). Dynamics of the hydrolysis was analyzed by Quartz Crystal Microbalance with Dissipation (QCM-D) technique.