Enzimas celulolíticas fúngicas e aplicação no branqueamento de polpa Kraft e na sacarificação de biomassa lignocelulósica

• Autor(a) principal: Pires, Silvana Rodrigues
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/326
• topic: Enzimas; Branqueamento; Polpa Kraft; Biomassa; Enzymes; Bleaching; Pulp Kraft; Biomass; CNPQ::CIENCIAS BIOLOGICAS::BIOQUIMICA::METABOLISMO E BIOENERGETICA

The sugarcane bagasse is a by-product with high carbohydrate concentration and available in great amount. It is constituted by cellulose, hemicellulose and lignin, that when joined form an extremely resistant compound to the attack of microorganisms. Many fungus produce hydrolytic enzymes, as cellulases and hemicellulases, capable to promote the hydrolysis of this biomass, liberating sugars for the fermentation. In this context, the production, purification and biochemical characterization of a xylanase of Fusarium oxysporum and your application in the process of bleaching of the pulp Kraft and in the saccharification of cane bagasse was realized. The xylanase exhibited molecular mass of approximately 21 kDa in SDS-PAGE. The protein was purified using ultrafiltration and ion exchange and molecular exclusion chromatography. The xylanase exhibited maxim activity at 60ºC and pH 6.0. The enzyme was capable of hydrolyze substrates as birchwood xylan and oat spelt xylan. The KM and Vmax values, using the substrate birchwood xylan were 0.85 mM e 0.23 μM/min, respectively. The enzymatic activity was inhibited by SDS, Fe+2, Cu+2, Al+3, among other and it was activated by Mg+2. The xylanase exhibited high thermostability at 50 ºC, with t1/2 of 26.1 h, what can be important for future industrial applications. The enzyme increased the rate of hydrolysis of the alkali-treated sugarcane bagasse significantly, when added it to the commercial cocktail cellulose. It was also evaluated the action of the xylanase in tests of bleaching of the pulp Kraft, in which the addition of the enzyme to the liqueur of bleaching promoted decrease of Kappa number. This work was also performed the cloning of an endoglucanase the cloning of an endoglucanase B produced by the fungous filamentous Aspergillus niger and your characterization in silico were accomplished. Computing analyses were executed with the sequenced fragment, as prediction of signal peptide and post-translational modifications. The cloned protein was designated AncEGLB (endoglucanase B from A. niger cloned). They were also accomplished, multiple alignments of sequence with other cellulases.