Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Lignocellulosic ethanol production obtained by enzymatic hydrolysis of carbohydrates to fermentable sugars and biological fermentation is one of the most promising alternatives for fossil fuel replacement. Its economical viability and commercialization depends largely on the final ethanol concentration in the fermentation media. High ethanol concentrations, superior to 4% (v/v), contribute to minimize the energy consumption during subsequent distillation and evaporation stages. This implies high sugars production during enzymatic hydrolysis, which can be achieved by increasing solids loading. Notwithstanding, high substrate consistency involves some drawbacks such as end-product inhibition and mixing difficulties. Furthermore, larger amounts of inhibitory compounds can be found, including phenolics from lignin, which can affect the optimal performance of fermenting organisms.
Known the capacity of laccases to decrease the toxicity of different media with high content of phenolic compounds, the effect of these enzymes was studied in saccharificaction and fermentation processes. Steam-exploded wheat straw was employed at different high solid loadings and Saccharomyces cerevisiae was used as fermenting organism. Laccase supplementation strongly reduced the phenolics content of broths, showing a positive effect on yeast performance and increasing significantly ethanol productivity.