Continuous production of xylooligosaccharides in a packed bed reactor with immobilized–stabilized biocatalysts of xylanase from Aspergillus versicolor

• An endo-xylanase from Aspergillus versicolor was immobilized on different agarose supports.
• The derivative xyl–glyoxyl–agarose was about 700 times more stable than the soluble enzyme.
• Glyoxyl derivative produced mainly xylobiose and little amount of xylose was observed only at the end of the hydrolysis.
• The catalytic activity was fully retained after 10 consecutive cycles of hydrolysis.
• The highly stable derivative was employed in a packed bed reactor for continuous synthesis of xylooligosaccharides.

The production of xylooligosaccharides (XOS) using a packed-bed enzymatic reactor was studied at lab-scale. For this, a xylanase from Aspergillus versicolor was immobilized on different supports. The optimal derivative was xylanase immobilized on glyoxyl-agarose supports. This derivative preserved 85% of its catalytic activity; it was around 700-fold more stable than the soluble enzyme after incubation at 60 °C and was able to be reused for at least 10 1 h-cycles retaining full catalytic activity. About 18% of oligosaccharides with prebiotic interest (X2–X6) were produced by the glyoxyl derivative in batch hydrolysis. The production of xylobiose was 2.5-fold higher using the immobilized preparation than with soluble enzyme and small concentrations of xylose (<0.1%) were observed only at the end of the reaction. The derivative was employed on a packed bed reactor, and the continuous operation with no recirculation reached 56% and 70% of the end of reaction with flow rates of 60 mL/h and 12 mL/h, respectively. In continuous operation with recirculation at a flow rate of 60 mL/h, the reaction was completed after four hours.

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