Interaction of Xylanase in Enzyme Cocktails for Saccharification of Pretreated Biomass

In order to maximize sugar yield in the enzymatic saccharification (i.e. conversion of complex carbohydrates to simple sugars) of pretreated biomass for cellulose-ethanol production, the use of "enzyme cocktails" has been recommended. The reason is that the complex carbohydrates in the biomass contain glucose and xylose as the main sugar units, plus a few other simple sugars such as arabinose and mannose; thus, enzymes to unlock these sugars from the complex carbohydrates must be appropriate for a particular sugar. For example, cellulases are a group of enzymes which attack cellulose, and xylanases are enzymes which attack part of the hemicellulose. Little is known, however, about how these enzymes interact in a cocktail mixture, when used for enzymatic saccharification. Research studies have been done to understand these interactions, in order to find an "optimum" mix of enzyme cocktail.

Researchers from the University of British Columbia "assessed the interaction between cellulase and xylanase enzymes and their potential to improve the hydrolysis (saccharification) efficiency of various pretreated lignocellulosic substrates when added at low protein loadings". The results showed that xylanase can have a "blocking effect', which can limit the accessibility of cellulases on cellulose. However, "the synergistic interaction of the xylanase and cellulase enzymes was also shown to significantly improve cellulose accessibility through increasing fiber swelling and fiber porosity and also plays a major role in enhancing enzyme accessibility". The full results are published in the open access journal, Biotechnology for Biofuels (URL above)