Produção de celulases e hemicelulases por Aspergillus fumigatus e A. niger utilizando sorgo biomassa como principal fonte de carbono

Abstract

The production of microbial cellulases and hemicellulases has been the subject of intense researches due to its wide use in the industrial and energetic sectors, for example, in the second generation ethanol production from agroindustrial wastes. In this work, the production of these enzymes was performed by Solid State Fermentation (SSF), using fungal strains of Aspergillus (A. fumigatus SCBM6 and A. niger SCBM1), in culture medium containing biomass sorghum (BS) and wheat bran (WB), as carbon sources and different nitrogen sources (peptone, yeast extract, ammonium sulfate and urea). Different SSF conditions were evaluated in order to select the best association between carbon and nitrogen sources for the induction of the production of hemi and cellulolytic enzymes. The production of five essential enzymes for the saccharification process of lignocellulosic biomass was evaluated (β-glucosidase, β-xylosidase, xylanase, exoglucanase and endoclucanase). The SSF performed with BS associated to peptone and A. niger SCBM1 as inoculum was selected as the best condition for the induction of the most of the enzymes mentioned, in which maximum production of xynalase and avicellase (exoglucanase) was obtained in 72 hours of (300.07 and 30.64 U/g, respectively), β-glucosidase and carboxymethylcellulose (endoglucanase) in 120 hours (54.90 and 41.47 U/g, respectively) and β-xylosidase in 144 hours (64.88 U/g). The chemical characterization of BS indicated the predominance of cellulose (39.84%) in BS, which may be associated to the most significant production of cellulases. The present work represents the first study in which sorghum biomass is used as a carbon source in the production of cellulases and hemicellulases by SSF, presenting it as a new and promising source of biomass for several biotechnological applications, such as the production of second generation ethanol.