Purificação e caracterização de xilanases do fungo Chrysoporthe cubensis e utilização na hidrólise de bagaço de cana-de-açúcar

• Autor(a) principal: Gomes, Kamila de Sousa
• Data de Publicação: 2014
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/2474
• topic: Chrysoporthe cubensis; Xilanases; Cana-de-açúcar; Chrysoporthe cubensis; Xylanase; Sugar cane; CNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA::ENZIMOLOGIA

Lignocellulosic biomass is the world s most natural source of carbohydrates, consisting mainly of cellulose, hemicellulose and lignin. Much of the biomass isn t used due to the difficulty of access to the plant cell wall hydrolytic enzymes, resulting in difficulty in degradation of the wall and their subsequent conversion into fermentable sugars. The search for alternative fuels is one area that encourages the hydrolytic enzymes production, besides the food industry and the pulp and paper industry, which has been using enzymatic processes increasingly. The aims of this work were the purification and characterization of xylanases from Chrysoporthe cubensis. The fungus was grown under solid state fermentation using wheat bran as carbon source. For enzymes purification, the enzymatic extracts were submitted to the ion exchange chromatography (Q-Sepharose) and gel filtration (Sephadex S-200). The xilanases molecular mass was approximately 21.5 kDa to P2 and 41.5 kDa to P3, under denaturing conditions. The xylanases present in P1 showed better performance at 60° and pH 4.0, P2 at 55° C C and pH 3.0. P3 showed better performance at 80 ° and pH 3.0. The oat C spelt xylan was the best substrate hydrolyzed by P1 and P3, and P2 beechwood xylan. CMC and ρ-NP-βXil were not hydrolyzed by any of the xylanases. The KM value, using oat spelt xylan as substrate, was 2.65 mg/mL to P1; 1.81 mg/mL to P2 and 1.18 mg/mL to P3. Xylobiose and xylotriose were the main hydrolysis products of oat spelt xylan indicating that xylanases act as endo-β-1,4-xylanases. Xylanases also proved to be efficient in the sugarcane bagasse hydrolysis, due to the increase in the reducing sugars concentration, indicating potential for the process of biomass saccharification.