Xylanase, xylooligosaccharide and xylitol production from lignocellulosic biomass: Exploring biovalorization of xylan from a sustainable biorefinery perspective

Abstract

The development of lignocellulose biomass (LCB) based platform chemicals and other byproducts has become imperative in order to reduce global carbon footprints and maximise utilization of renewable energy sources. LCB derived xylan is an abundantly accessible feedstock that can be subjected to pretreatment and enzymatic bioconversion using microbe-derived xylanolytic secretomes. The enzymatic breakdown of xylan into xylooligosaccharides (XOS) and xylose requires synergistic action of xylanases and other debranching enzymes. XOS, being short chain oligosaccharides, act as substrates to establish the commensal microbiome in the lower gut of animals and exhibit prebiotic properties. Further, D-xylose, a pentose sugar, obtained from xylan hydrolysis can be converted into xylitol (C5H12O5) which is widely used in food and pharmaceutical industries as an alternative sweetener. The researchers have extensively reviewed cellulose-based biorefineries that focus on integrated product generation. However, valorization of hemicellulosic xylan extracted from agricultural biomass to generate industrially relevant products requires a comprehensive analysis. This article, therefore, highlights sustainable operations using LCB for the production of xylanolytic enzymes, xylooligosaccharides and xylitol. Insights into knowledge gaps and technological challenges have been discussed with a focus on enzymatic hydrolysis of LCB xylan and multi-product framework from a biorefinery standpoint.