LAUSR

Abstract The production of xylooligosaccharides (XOS) was evaluated using immobilized and stabilized biocatalysts of a commercial enzymatic cocktail, Bioxilanase L PLUS (BIO), which is based on the xylanolytic enzymes produced by Trichoderma reesei . BIO was immobilized by multipoint covalent attachment under alkaline conditions on agarose beads highly activated with aldehyde groups (Ag-G BIO) resulting in a highly active and stable biocatalyst (half-life was approximately 50 h at pH 7.0 and 60 °C). Ag-G BIO was 10-fold more stable than soluble preparation at pH 7.0 and 60 °C. Ag-G BIO was also physically modified by surface coating with polyethyleneimine (PEI) which promotes an ionic interaction with the anionic groups of the enzyme surface. Ag-G BIO covered with a layer of PEI 10 kDa (Ag-G BIO-PEI 10) was >100-fold more stable than soluble BIO preparation. The optimal biocatalyst (Ag-G BIO-PEI 10) allowed to perform ten cycles of beechwood xylan hydrolysis reaction at high concentration (4% (w/v)) with a high conversion degree (>80%). Moreover, Ag-G BIO-PEI 10 reached 90% of conversion in only 8 h and so, it could be used for short reaction times, which would extend its useful life, thus allowing its application for industrial processes.