Xylanases (EC 18.104.22.168; endo-1,4-b-xylanase) and xylosidases (EC 22.214.171.124; xylan 1,4-b-xylosidase) are glycosidases that catalyze, respectively, the hydrolysis of the 1,4-b-xylosidic linkages of xylans and the hydrolysis of xylooligosaccharides and xylobiose, producing xylose. The xylan-degrading enzymes of several microorganisms have been extensively studied during the last decade, because of their importance in many industrial processes, for example, in clarification of juices and wines, bread manufacture, xylose and xylitol productions; they are also used in the beer, animal feed, paper and cellulose industries. Although they have plenty of applications, these enzymes have not all their potential explored. Their immobilization on solid supports offers a lot of advantages, including the reuse of the enzyme, the easy separation of the product, and the increase of enzymatic stability. The objectives of this work are: a) to produce the thermophilics enzymes xylanase and xylosidase, by using a fungi isolated in the laboratory (FCUP1), besides Humicola grisea var. thermoidea and Aspergillus versicolor; b) to accomplish multipoint covalent immobilization of thermophilics xilanases and xylosidases of filamentous fungi in solid supports, with kinetic characterization of those more actives and stabilized derivatives, comparing them with the free enzymes; c) to accomplish the hydrolysis of xylan using, concomitantly, xylanase and xylosidase derivatives; d) to evaluate the reuse capacity of the actives and stabilized derivatives. Immobilization studies of thermostable xylan-degrading enzymes are scarce, but fundamental to optimization and cost reduction in the many applications.
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