Fermentação em batelada da biomassa lignocelulósica de capim elefante (Pennisetum purpureum) para produção de etanol 2g

Abstract

The solid and growing demand for fuels, associated with the numerous positive variations in the price of a barrel of oil in recent decades, evidences, with each decade, the need to diversify the energy matrix of countries. Brazil, for example, has an internal demand of approximately 32.6 billions liters of ethanol per year, mainly due to its mandatory use in the mixture of fuels for transport. In this sense, the present work proposed to carry out pre-treatment tests, enzymatic hydrolysis and batch fermentation of elephant grass (Pennisetum purpureum) biomass – a competitive lignocellulosic culture for obtaining ethanol due to low production costs and high levels of agricultural productivity. For this work, two alkaline pretreatment methodologies were carried out followed by enzymatic hydrolysis (2 % (v/m) Cellic Ctec2 and 0.5 % (v/m) Cellic Htec2) to obtain fermentable sugars. The pre-treatments proved efficient in making cellulose available and removing the lignin content. The hydrolysates obtained showed 19.9 and 25.6 g/L 2 of total sugars. Then, three fermentation conditions were carried out in each hydrolyzate: (i) fermentation carried out by the wild yeast strain Meyerozyma caribbica (CHAPE-096), isolated from decomposing corn husk; (ii) fermentation carried out by the industrial strain of Saccharomyces cerevisiae (PE-02) and; (iii) by a combination of Saccharomyces cerevisiae (PE-02) and Meyerozyma caribbica (CHAPE-096) strains in a 1:1 (v/v) ratio. A maximum ethanol concentration of 0.42 getanol/glucose was reached through the combination of S. cerevisiae and M. caribbica strains, representing 83% of maximum theoretical yield (0.511 getanol/glucose). The sub-product xylitol was also obtained in this study, with a maximum concentration of 0.61 gxylitol/gxylose from the xylose consumed by the industrial strain S. cerevisiae.