(235d) Novel Model for Simultaneous Enzymatic Hydrolysis of Cellulose and Hemicellulose Considering Morphologies

Lignocellulosic biomass has been recognized as an important energy feedstock for its abundance and potential to produce biofuels. Few models have been constructed for enzymatic hydrolysis of lignocellulosic substrate. The variety of the components contained in the lignocellulosic substrate and the complexity of the enzymes acting on this heterogeneous substrate make the model constructing work difficult, especially the functionally based models which describe the mechanistic details of hydrolysis. Most of the functionally based models only considered one component of lignocellulosic substrate (i.e. cellulose or xylan) and used simplified representations for the structure of substrate. For example, in most of the models for cellulose hydrolysis, the cellulosic substrate was described as an assembly of isolated glucan chains without obstructive interactions. Such simplified representation limits the ability of models to predict finial conversion of cellulose. Our previous model for cellulose hydrolysis avoided the unrealistic simplification and considered the cellulosic substrate morphology and its hydrolytic evolution.  

In the current work, we construct a novel functionally based model for lignocellulosic substrate hydrolysis. Due to the variety of the components contained in the lignocellulosic substrate, this model will consider: (1) more types of chains in the lignocellulosic substrate than just glucan chains; (2) more types of monomer units contained in the lignocellulosic substrate than just glucose units; and (3) side groups or side chains associated with hemicellulose. These components are considered in an integrated meaning where lignocellulosic morphology is conceptually represented. The present work mainly focused on the description of improving the substrate morphology and the surface bond site formalism. As important factors that slow down the hydrolysis rate and limit the final conversion of substrate, we also incorporate both the product inhibition and the enzyme degradation effect in our model. This functionally based model for lignocellulosic substrate hydrolysis is developed in full generality for any types of lignocellulosic substrate and any number of enzymatic species. The effectiveness of the novel model is illustrated on comparison with real experimental measurements.