Monday, April 30, 2012
Napoleon Ballroom C-D, 3rd fl (Sheraton New Orleans)
The development of renewable sources of energy has been considered overriding in a global level. Within this context the production of ethanol from the biomass (2G) residue of the sugarcane sucrose and 1G ethanol production in Brazil is particularly attractive. The necessary enzymatic hydrolysis of the biomass involves the use of cellulases, hemicellulases and accessory enzymes whose cost has hindered 2G ethanol production. The present work studied the production of xylanase, β-glucosidase β-xylosidase and α-arabinofuranosidase by the fungus Aspergillus awamori using the hemicellulosic fraction generated from the hydrothermal (hot-compressed water) treatment of sugarcane bagasse, as the growth medium carbon source, aiming to decrease the cost of enzyme production. The hydrothermal pretreatment was performed in a pressure reactor using 10% w/v of sugarcane bagasse, under agitation and initial pressure of 20 bar (N2). Based on a statistical experimental design, the optimum reaction temperature and residence time were found to be 170 °C and 40 minutes, respectively. In a growth medium presenting xylan 0.50% (pH 5.0) Aspergillus awamori was able to, efficiently, produce xylanase (45,000 UI/L), β-glucosidase (3,300 UI/L), β-xylosidase (240 UI/L) and α-arabinofuranosidase (600 UI/L), irrespective of the presence of furfural at 0,74%, acetic acid at 0,25% and hydroxymethylfurfural at 0,02%. These results are promising as the use of the biomass xylan stream for enzyme production would greatly improve the economics of 2G ethanol, via enzymatic hydrolysis.
Keywords: Aspergillus awamori, sugarcane bagasse, hot-compressed water treatment, β-glucosidase, xylanase, β-xylosidase, α-arabinofuranosidase.