Enzymatic hydrolysis of cellulose: linking hydrolyzability with cellulose characteristics

Liberation of fermentable soluble sugars from cellulosic 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 cellulosic 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 cellulose have an effect of enzymatic hydrolysis efficiency. The focus of the present work was structural characterization of cellulose during the course of hydrolysis which indirectly gives information about the interaction between the enzymes and the substrate. The overall aim was to understand the limitations in enzymatic hydrolysis of cellulosic biomass. Enzymatic hydrolysis was studied on industrial-like cellulosic substrates, resulting from alkaline pulping of softwood. Enzymatic hydrolysis of cellulosic 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. 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)