Sunday, May 4, 2008
4-31

Bioethanol production from different cellulosic sources using Simultaneous Saccharification and Fermentation

Verônica Ferreira, Mariana de Oliveira Faber, and Nei Pereira Jr.. Biochemical Engineering Department, Federal University of Rio de Janeiro, CT, Bl E, Cidade Universitária, 21949-900, Rio de Janeiro, Brazil

The search for new technologies for plant biomass conversion into alternative fuels is leveraged by many social and environmental problems associated with the use of fossil fuels and their exploration. Cellulose, the major component of plant biomass, is a polysaccharide hydrolysable by three different cellulolytic enzymatic groups: endoglucanases, exoglucanases and b-glucosidases. This complex enzymatic system is inhibited by its final hydrolysis products, particularly glucose. To circumvent this problem and make the ethanol fermentation from cellulose technically feasible, a process known as Simultaneous Saccharification and Fermentation (SSF) should be adopted. It combines enzymatic hydrolysis and sugar fermentation to ethanol, and can be enhanced with the use of thermostable enzymes and yeasts. This study aimed at evaluating the enzymatic hydrolysis of three different cellulosic sources (carboxymethyl cellulose, crystalline cellulose and sugar cane bagasse cellulignin) and comparing their fermentability between a recombinant Saccharomyces cerevisiae harboring the b-glucosidase gene from Humicola grisea with a commercial yeast strain used in bakery. The experiments were performed at 37°C, 20% (w/v) of cellulosic source concentration and 25 FPU of commercial enzyme/g of cellulosic material. The recombinant strain displayed superiority on the conversion of the resulting enzymatic hydrolysis products in comparison with the bakery yeast. The best results with the recombinant strain were obtained with the more complex cellulosic substrate (bagasse cellulignin), achieving an ethanol concentration of 55 g.L-1 after 60-hour SSF process. The studied system shows great biotechnological potential for bioethanol production from lignocellulosic feedstock.

See more of Poster Session One
See more of General Submissions

See more of The 30th Symposium on Biotechnology for Fuels and Chemicals (May 4 -- 7, 2008)