The role and applications of xyloglucan hydrolase in biomass degradation/bioconversion

Abstract

Lignocellulosic biomass is currently the most promising alternative energy source for realizing sustainable demands of agrarian economies. Its natural recalcitrance to degradation necessitates a detailed study on the complex biochemistry involved in bioconversion of this lignin–carbohydrate complex. A comprehension of the enzymology and role of principal and accessory glycosyl hydrolases involved in biomass degradation are, hence, noteworthy in this context and the xyloglucan-active hydrolases warrant special mention. These are enzymes which carry out hydrolysis and transglucosylation of xyloglucan, the major hemicellulosic polysaccharide in plant biomass. The structurally complex xyloglucans cover and cross-link the cellulosic microfibrils in plant cell walls and make cellulose inaccessible to saccharification by cellulases. Solubilisation of biomass polysaccharides and release of sugars are central to the biomass-to-bioethanol process. Complete conversion of biomass carbohydrates requires a suite of hydrolytic enzymes, which may be designed specifically to accommodate the predominant and subsidiary biomass-cleaving enzymes. Xyloglucan hydrolases which are known to act synergistically with cellulases and xylanases in loosening the plant cell wall are vital enzymes to be deployed for successful bioconversion processes. This chapter is an insight into the capacity of these accessory, but indispensable, hydrolytic enzymes in unlocking the inaccessible biomass polysaccharides for increased sugar recovery and thereby, in drafting the fuels of future.