(483e) Production of Ethanol from Cassava Stems with E. coli Modified

Mitigation of the environmental and economic effects of energy non-renewable sources has prompted the use of ethanol from lignocelluloses materials as an alternative fuel. The stems of cassava, variety Copiblanca represent an annual output of 779,182 tons in Colombia. Currently these stems are used in power generation and for animal consumption, but most of it is discarded in the field.

The aim of this study was to evaluate the production of ethanol from cassava stems. Hydrothermal and dilute acid pretreatment was used. Fermentation and saccharification were either independent (SFI) with E. coli (MS04 ) and saccharomyces cerevisiae (ethanol red).

Simultaneous saccharification and fermentation (SFS) was also evaluated with the yeast. A central composite design for each pretreatment and the SFS was performed. The acid (H2SO4 and 164°C ) pretreatment achieved the highest yield of fermentable sugars (0.85%). In the SFI, ethanol production increase to 8.9 g/L with E. coli after 24 h of reaction and a productivity of 0.37 g/Lh ethanol. The yield of Saccharomyces cerevisiae was 47.70% with a productivity of 0.24 g/Lh.

SSF was carried out with inoculum concentrations varying from 4 to 11g/L and an enzyme activity in the between of 1.59 and 4.41 FPU/mL). After 24 hours of fermentation ethanol concentration was 1.09 g/L, the yield 86% and the productivity 0.44 g/Lh.