Produção de açúcares fermentáveis para produção de etanol de segunda geração utilizando endoglucanases de fungo filamentoso

Abstract

The growing global demand for ethanol necessitates the development of secondgeneration technologies to avoid supply limitations and competition for land use in energy production. A promising alternative is the production of ethanol from lignocellulosic biomass, found in agro-industrial residues and renewable sources. This study explored the production of endoglucanases through solid-state fermentation using the fungus Penicillium roqueforti ATCC 10110 and lignocellulosic residues such as sugarcane bagasse (SCB), coconut shell (CC), pineapple crown (PC), and wheat bran (WB) as substrates. The crude enzymatic extract was characterized by evaluating its thermostability, stability at different pH levels, and activity in the presence of metals and organic solvents. The enzyme was applied in the saccharification of SCB, CC, WB, cocoa fruit husk (CFH), and cocoa seed shell (CSS), with scanning electron microscopy confirming the efficiency of the process. The optimization of factors influencing saccharification was carried out using the Box-Behnken experimental design, identifying optimal conditions of 6 hours of incubation, 15% substrate, and 440 U/mL enzyme concentration, resulting in 253.19 mg/g of reducing sugars. As an alternative, the enzymatic extract was immobilized on activated carbons derived from cocoa shell and treated with solid-state fermentation using Penicillium roqueforti (CAPr), Aspergillus niger (CAAn), and a control (CAC). Enzyme adsorption was confirmed by scanning electron microscopy, and the characterization indicated that the immobilized enzyme exhibited a broader activity range at 80°C and pH 2 to 13, maintaining 80% activity after 120 days. The immobilized enzyme retained relative activity of 30%, 33%, and 32% after five cycles for CAPr, CAAn, and CAC, respectively. The efficiency of pre-treating SCB and Sargassum vulgare (SVU) with diluted acid before applying the enzymatic extract was also evaluated. The analysis demonstrated that SCB has a high hemicellulose content, while SVU has less than 3% lignin, favoring its use without prior treatment. Characterizations by FTIR and XRD confirmed the effects of the pretreatment, and HPLC identified the types of sugars produced. These results highlight the potential of the obtained endoglucanase for industrial application.