Production of prebiotic xylooligosaccharides from arabino- and glucuronoxylan using a two-domain Jonesia denitrificans xylanase from GH10 family

Abstract

Development of a more environmentally sustainable society is based on the maximum use of renewable carbon sources and their valorization of environmentally-friendly green technologies. This includes a thorough use of plant biomass and agricultural residues for the production of value-added bioproducts. Xylan is the second most abundant biopolymer in nature which can be sustainable converted into pentoses and xylooligosaccharides, that have wide applications in the food, feed, pharmaceutical, and cosmetic industry. Within the scope of present study, we biochemically characterized two-domain GH10 xylanase from Jonesia denitrificans (JdXyn10A) and evaluated its applicability for production of xylooligosaccharides (XOS). JdXyn10A has a specific activity of 84 ± 2 U/mg and 65 ± 5 U/mg when acting on beechwood glucuronoxylan and rye arabinoxylan, respectively. The enzyme is stable in a wide pH range and is tolerant to high concentrations of NaCl and ethanol. Interestingly, the profile of products released by the enzyme is predominant in xylobiose and xylotriose, with a very low fraction of xylose which is desirable for XOS production. The efficiencies of enzymatic conversion of beechwood glucuronoxylan and rye arabinoxylan are 47.67 % and 26.01 %, respectively, after 6 h of enzymatic hydrolysis only. Structural comparison between the JdXyn10A homology model and the structure from its homologous that while the glycone region of its active site is well preserved, the aglycone region presents structural differences in the +2 subsite that may explain why JdXyn10A does not release xylose.