Produção de celulases a partir de capim elefante (pennisetum purpureum) por fermentação em estado sólido

Abstract

The possibility of a shortage of fossil fuels and concerns about the environment has led to the need for alternative sources for fuel production. One of the alternatives is the production of the Second Generation Ethanol (2G) using lignocellulosic biomass, such as elephant grass (Pennisetum purpureum). In this process there is use of enzymes that make the degradation of the biomass, leaving the process very expensive, then a solution would be the production of these enzymes from fungi. The objective of this work was the production of fungal cellulase enzymes from elephant grass by solid state fermentation (FES). The fungi screening was performed to select the species Aspergillus niger I, Trichoderma viride and Trichoderma asperellum for FES. Using experimental planning, the influence of factors such as initial moisture and pH were verified. From the FES optimal condition the enzymatic extract was obtained, which in turn was used in the hydrolysis of pre-treated elephant grass to generate the fermentable sugars. Mathematical modeling was also developed to study the kinetics of enzymatic hydrolysis. The fungus that stood out in the production of the total cellulases (FPase) and endoglicanases (CMCase) was T. viride, obtaining 35 U g -1 and 39 U g -1, respectively, with initial moisture in the FES of 80% and pH 5.0. In the hydrolysis assays, the concentration of 40 g L -1 substrate (pre-treated elephant grass) was used to evaluate the kinetic profiles of the production of reducing sugars (RS). The specie that most stood out in the enzymatic hydrolysis was the T. viride obtaining in 12h of hydrolysis 8,4 g L -1 of reducing sugars. In the mathematical modeling of the hydrolysis it was possible to observe that for the enzyme obtained from the FES and for the commercial enzyme used for comparison, that the higher the initial enzyme concentration, the higher is the initial reaction rate.