Avaliação de complexos enzimáticos obtidos a partir de fungos do cerrado para produção de etanol de segunda geração

Abstract

The exhaustion of oil, coal and natural gas, combined with the increase in global energy demand, has led to research new ways of producing alternative fuels such as ethanol from second generation. This is being produced by the hydrolysis and fermentation of lignocellulosic materials since the late nineteenth century, but only in the last 20 years, this technique has been proposed to meet the fuel market. Thus, the study of the production of second generation ethanol proves interesting by the possibility of taking advantage of agroindustrial residues such as bagasse from sugarcane which is an abundant lignocellulosic residue in Brazil, and the use of micro-organisms intended for production of enzymes for hydrolysis of lignocellulosic biomass. The micro-organisms that produce cellulose complex can be found in the Brazilian Cerrado, since it holds about 5% of the planet s biodiversity, considered the richest savanna in the world. The solid state fermentation represents an important step for the production of the enzyme complex, possessing advantages, such as less effluent generation, low contamination risk, low operating cost, and the possibility of reuse of various types of agro-industrial residues. In this work was done a benchmarking the production of the enzyme complex by Cerrado fungi and Aspergillus niger. Three Cerrado fungi were evaluated and compared with Aspergillus niger in the ability to produce ethanol by use of the enzyme complex and Saccharomyces cerevisiae under different conditions of solid state fermentation (SSF) and submerged fermentation (SF) of exploded sugarcane bagasse. Among the fungi tested was found that the Chrysonilia sitophila stood out as promising, and the best conditions associated with ethanol production were: a) 72 hours of SSF using sugarcane bagasse and rice bran at a ratio of 1/3 and 2/3; b) 48 hours of SF using 80% of exploded sugarcane bagasse and 20% of raw bagasse. In the best conditions were observed 6,5 g/L of ethanol production after one alcoholic fermentation and 16,7 g/L of ethanol after four successive fermentations with successive enzyme complex production.