Análise de diferentes misturas enzimáticas do fungo Humicola grisea var. thermoidea na hidrólise da fração de hemicelulose de bagaço de cana-de-açúcar
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2011-08-31
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Universidade Federal de Goiás
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The biomass consists mainly of cellulose, hemicellulose and lignin. Cellulose is the most abundant polymer xylan and the main component of hemicellulose. Enzymatic hydrolysis is an important step in the bioconversion of cellulose and hemicellulose fraction of lignocellulosic residues. However, for the conversion of the hemicellulose, the substrate must undergo a pretreatment step which allows the refining of biomass at the microscopic level, separating the same into its main components (cellulose, hemicellulose and lignin) or loosening the fibers of its components, facilitating the accessibility of enzymes to hemicellulose chain. The conversion of cellulose and xylan to glucose and xylose may be performed by a group of enzymes produced by bacteria and fungi. The thermophilic fungus Humicola grisea var thermoidea produces an efficient complex of cellulolytic enzymes (endoglucanases, cellobiohydrolases and β-glucosidase) and xylanolítics (endoxylanases and β-xylosidase) with high thermal stability when cultivated in different lignocellulosic substrates. The aim of this study was to analyze the efficiency of enzymes
produced by H.grisea in the hydrolysis of the hemicellulose fraction of sugarcane bagasse (BCA). BCA assays used in the hydrolysis was subjected to alkaline pretreatment (Treatment I, II and III) and steam explosion. BCA pretreated was subsequently hydrolyzed with different enzyme mixtures using culture supernatant of the fungus H. grisea supplemented with recombinant enzymes endoxylanase (HXYN2r), cellobiohydrolase (CBH1.2r) and β-xylosidase (XYNB2r). The results showed that the pre-treatment was most suitable to steam explosion which revealed a yield of about 78% xylan. The best enzyme formulation was a mixture of the supernatant of culture of H. grisea (SHG) grown in wheat bran (WB) and BCA supplemented with HXYN2r (950 U), CBH1.2r (950 U) and XYNB2r (1.17 U).
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FARIA, S. P. Análise de diferentes misturas enzimáticas do fungo Humicola grisea var. thermoidea na hidrólise da fração de hemicelulose de bagaço de cana-de-açúcar. 2011. 114 f. Dissertação (Mestrado em Ciências Biológicas) - Universidade Federal de Goiás, Goiânia, 2011.