Paludibacter propionicigenes GH10 xylanase as a tool for enzymatic xylooligosaccharides production from heteroxylans

Bioconversion of lignocellulosic biomass into value-added products relies on polysaccharides depolymerization by carbohydrate active enzymes. This work reports biochemical characterization of Paludibacter propionicigenes xylanase from GH10 (PpXyn10A) and its application for enzymatic xylooligosaccharides (XOS) production from commercial heteroxylans and liquor of hydrothermally pretreated corn cobs (PCC). PpXyn10A is tolerant to ethanol and NaCl, and releases xylobiose (X2) and xylotriose (X3) as the main hydrolytic products. The conversion rate of complex substrates into short XOS was approximately 30% for glucuronoxylan and 8.8% for rye arabinoxylan, after only 4 h; while for PCC, PpXyn10A greatly increased unbranched XOS yields. B. adolescentis fermentation with XOS from beechwood glucuronoxylan produced mainly acetic and lactic acids. Structural analysis shows that while the glycone region of PpXyn10A active site is well preserved, the aglycone region has aromatic interactions in the +2 subsite that may explain why PpXyn10A does not release xylose.

The potential of tailoring the conditions of steam explosion to produce xylo-oligosaccharides from sugarcane bagasse

In this study, the potential of the steam explosion (SE) method to produce high levels XOS from sugarcane bagasse, a xylan-rich hemicellulosic feedstock, was assessed. The effect of different operating conditions on XOS production yield and selectivity were investigated using a mini-pilot scale SE unit. The results show that even under a non-optimized condition (190 °C, 5 min and 0.5% H₂SO₄ as catalyst), SE led to about 40% xylan recovery as XOS, which was comparable to the well-known, multi-step, enzymatic production of XOS from alkaline-extracted xylan, and other commonly employed chemical methods. In addition, the XOS-rich hydrolysate from SE constituted of greater diversity in the degree of polymerization, which has been shown to be desirable for prebiotic application.