Doença celíaca

Introduction
Discovered four decades ago by Reese and Mandels
[1,2], the cellulolytic enzyme system secreted by the filamentous fungi Trichoderma reesei (synonym Trichoderma viride) is the initial parent of most fungal strains for industrial cellulase production. The hydrolysis step converting cellulose to glucose is recognized as the major limiting step in the development of biological processes for production of biofuels from lignocellulosic raw materials because of the low efficiency of cellulases and their cost.
The enzymatic hydrolysis of cellulose involves three types of cellulases (cellobiohydrolases, endoglucanases and b-glucosidases) working in synergy [3]. Endoglucanases
(EC 3.2.1.4) randomly cleave the b-1,4 glycosidic linkages of cellulose; cellobiohydrolases (EC 3.2.1.91) attack cellulose chain ends to produce the constitutive unit of cellulose, cellobiose (a dimer of glucose linked by a b-1,4 glycosidic bond); and b-glucosidases (EC 3.2.1
21) hydrolyse cellobiose into two molecules of glucose.
In fact, enzymatic hydrolysis of cellulose is a six-step complex process, the last step being a homogenouscatalysis reaction involving the action of b-glucosidase on cellobiose. Cellobiose is a strong inhibitor of both cellobiohydrolases and endocellulases, and the b-glucosidase action can reduce its effect. In addition, the produced glucose also inhibits cellulolysis, although to a lesser extent [4]. Unexpectedly, the amount of b-glucosidase-
1 (BGL1) generated by T. reesei hyperproducing strains represents a very low percentage of the total secreted proteins [3,5]. This very low level of b-glucosidase activity [6] often limits the amount of this enzyme in commercial cellulase preparations. This limitation can be alleviated either by overexpressing b-glucosidase in
T. reesei or by adding extra b-glucosidase from other sources [7,8]. Supplementing the native T. reesei enzymatic cocktail with b-glucosidase from other fungi is