Aspergillus nidulans is poorly exploited as a source of enzymes for lignocellulosic residues degradation for biotechnological purposes. This work describes the A. nidulans Endoglucanase A heterologous expression in Pichia pastoris, the purification and biochemical characterization of the recombinant enzyme. Active recombinant endoglucanase A (rEG A) was efficiently secreted as a 35？kDa protein which was purified through a two-step chromatography procedure. The highest enzyme activity was detected at C/pH 4. rEG A retained 100% of activity when incubated at 45 and C for 72？h. Purified rEG A kinetic parameters towards CMC were determined as ？mg/mL, ？mmol/min, and 55.8？IU (international units)/mg specific activity. Recombinant P. pastoris supernatant presented hydrolytic activity towards lignocellulosic residues such as banana stalk, sugarcane bagasse, soybean residues, and corn straw. These data indicate that rEG A is suitable for plant biomass conversion into products of commercial importance, such as second-generation fuel ethanol. 1. Introduction One of the major challenges of modern society is to promote economic growth in a sustainable model. Global demands of energy consumption stimulate the research on alternative fuels, aiming the reduction of the dependence on nonrenewable energy sources. For some decades now, Brazil and the USA have successfully produced bioethanol from sugarcane and corn, respectively. Nonetheless, plant biomass generated by extensive cultures, and which is not totally converted into useful by-products such as fertilizers and animal feed, tends to accumulate and cause environmental problems. Numerous efforts have been made in order to develop biotechnological routes to produce the so-called second-generation bioethanol from agriculture residues such as corn stover, rice straw, sorghum bagasse, corncobs, wheat bran, wheat straw, and sugarcane bagasse. The limiting step of this process is the availability of low-cost efficient enzymes to convert lignocellulose into fermentable glucose units. Filamentous fungi can produce and secrete enzymes which efficiently degrade cellulose, a linear polymer of glucopyranose units connected by β-1,4 bonds, to oligosaccharides and glucose. Based on model organisms from the genera Trichoderma and Phanerochaete, fungi cellulolytic enzymes acting in synergism have been classified as (1) endoglucanases or endo-β-1,4-glucanases (EC 3.2.1.4), responsible for the random attack of internal glycosidic bonds of the cellulose amorphous region, generating oligosaccharides of various sizes and new chain ends
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