Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
Second-generation ethanol production from lignocellulosic materials depends on three main processes: biomass pretreatment, enzymatic hydrolysis, and fermentation. The cost-effective saccharification of pretreated hemicellulose rich feedstocks into fermentable sugars requires beside cellulases accessory enzymes such as xylanases and pectinases. An alternative to reduce enzyme costs, a bottleneck of enzyme hydrolysis, is the use of agro-industrial wastes as carbon sources for enzyme production. Acrophialophora nainiana has been reported to be a good hemicellulase producer and is able to grow on a variety of lignocellulosic materials. In this work, enzyme preparations of A. nainiana were produced by growing it in submerged culture medium containing 1.0% (w/v) banana stem, sugarcane bagasse, dirty-cotton residue or cellulose as C-source. Enzyme activities (xylanase, pectinase, FPAtotal, FPAsoluble, FPAinsoluble, CMCase and β-glucosidase) and the saccharifying power on biomass of the enzymatic pools were characterized. Hydrolysis experiments were carried out at 50°C for 48 hours with 1.0% (w/v) of untreated and pretreated (steam exploded, sulphuric acid) sugarcane bagasse. The kinetic profiles were assessed by a fractal kinetic model. Results indicate banana stem as the best carbon source for hydrolytic enzyme production with A. nainiana. The enzymatic pool produced with banana stem promoted the highest saccharification of sugar-cane bagasse and steam explosion was the most effective pretreatment technology to obtain substrates accessible to enzymes, once presenting higher values of k and lower h.