Resumo

There is an increasing interest in cellulose/hemicellulose hydrolysis aiming the development of cost-effective processes to use lignocellulosic biomass for bioethanol production. In Brazil sugarcane bagasse and trash (cane leaves and tops) appear as attractive options for cellulosic ethanol production. The enzymatic treatment is the most promising method for an efficient hydrolysis of lignocellulosic residues, and enzymatic cocktails containing cellulases, hemicellulases and ligninases are required for an efficient saccharification, resulting in higher yields of fermentable sugars with lower enzyme loads. In this study we investigated the hydrolysis of raw sugarcane trash (RSCT) and sugarcane bagasse, both in natura (SB) and steam-exploded (SSB), using crude culture extracts from fungal strains of Colletotrichum graminicola and Pycnoporus sanguineus isolated from the Amazon soil. Mixtures of these two extracts (CGPS) were added of aliquots of cellulase-rich Trichoderma reesei crude culture extracts (TR) or Celluclast® 1.5L (Novozymes). The production of cellulases, hemicellulases and laccases by C. graminicola and P. sanguineus in wheat bran supplemented with agroindustrial residues, low cost media, was previously optimized using Response Surface Methodology. The hydrolysis of RSCT, SSB and SB at 1% (w/v) final concentration was estimated at 50°C and 180 rpm, in 50 mmol/L acetate buffer, pH 5.0, containing 10 mmol/L sodium azide. The use of mixtures of CGPS and Celluclast® resulted in maximal reducing sugars yields of 32%, 43% and 53%, and glucose yields of 28%, 49% and 35% for RSCT, SSB and SB hydrolysis, respectively, after 48 h. In contrast, maximal yields of 50%, 81% and 77% in reducing sugars and 36%, 63% and 50% in glucose, respectively, after only 24 h, were obtained using mixtures of CGPS and TR. The higher efficiency of the CGPS/TR cocktail compared to that of the CGPS/Celluclast® cocktail reveals its excellent potential for application in lignocellulosic biomass hydrolysis processes.