Enzymatic Hydrolysis of Industrial Derived Xylo-oligomers to Monomeric Sugars for Potential Chemical/Biofuel Production

Commercial grade, xylo-oligosaccharide-rich, water-soluble streams, obtained after hydrothermal pretreatment of wheat straw, were assessed for their potential as sugar feedstocks to make glycol. When acid and enzymatically based hydrolysis processes were compared, it appeared there was considerable potential to further optimize the enzymatic approach of hydrolyzing the oligomers to pure xylose. Various commercial enzyme cocktails and their synergistic cooperation were assessed over a range of combinations and hydrolysis conditions. An optimized enzyme cocktail, at low protein loadings, could hydrolyze more than 80% of the oligomers to xylose within 3 h. After 24 h, all of the xylo-oligomers were hydrolyzed to xylose. A moderately adjusted pH of 4.3 ensured fast and efficient hydrolysis without the need for agitation. The advantage of an enzymatic as opposed to an acid-based approach to hydrolysis was evidenced when the process was scaled up to 300 L. These include the use of a cheaper and simpler infrastructure, improved xylose recovery, and a much easier xylose purification process. This indicated the potential for further enzyme recycling and reuse, further enhancing the economic attractiveness of an enzyme-based approach.