Preparation of a robust immobilized biocatalyst of β-1,4-endoxylanase by surface coating with polymers for production of xylooligosaccharides from different xylan sources.

Xylooligosaccharides display interesting prebiotic effects on human health. The endoxylanase Xys1Δ, from Streptomyces halstedii JM8, was immobilized and stabilized on glyoxyl-agarose beads by multipoint covalent attachment using a novel strategy based on surface coating with a multilayer of polymers. The optimal modification consisted of surface coating with a bilayer formed by a layer of derived dextran polymers and a layer of polyethylenimine. The optimized biocatalyst was 550-fold more stable than one-point covalent immobilized Xys1Δ (at 70 °C, pH 7). This biocatalyst was tested for the production of xylooligosaccharides from soluble xylans from various sources. Hydrolysis of beechwood, wheat straw and corncob xylans was 93% in 4 h, 44% in 5 h and 100% in 1 h, respectively. Maximum values of xylooligosaccharides were found for beechwood at 20.6 mg/mL, wheat at 12.5 mg/mL and corncob at 30.4 mg/mL. The optimized biocatalyst was reused for 15 reaction cycles without affecting its catalytic activity.