Monday, May 2, 2011
Grand Ballroom C-D, 2nd fl (Sheraton Seattle)
Recovery of agricultural wastes as raw material allows to add value to those residues which helps to minimize pollution caused by its accumulation. Sugarcane bagasse and dirty cotton are residues of the sugar and textile industries, respectively with potentials biotechnological applications for the production of holocellulases-degrading cell wall by species of Aspergillus. Among the enzymes secreted by Aspergillus nidulans, A. oryzae and A. terreus, xylanases, pectinases and endoglucanases were the most active when grown on agro-industry residues. Xylanases from A. nidulans and A. terreus grown on sugarcane bagasse, and A. oryzae grown on dirty cotton residues as the carbon sources were purified by ultrafiltration followed by gel filtration and ion-exchange chromatographies. Enzymatic activities were measured by DNS method using xylose as the standard sugar. The profile of purification was visualized by SDS-PAGE stained with silver nitrate. Xylanases of 21.5 and 34.7 kDa (Xyl N1 and Xyl N2) from the ultrafiltrate and retentate, respectively, were purified from A. nidulans, and a xylanase of 21.5 kDa (Xyl O1) was purified from the ultrafiltrate of A. oryzae. Xyl T1 and T2 from A. terreus revealed two main protein bands, being possibly two different xylanases. The effects of temperature and pH on enzymatic activity revealed that the enzymatic catalysis higher at 50°C for all enzymes and pH values between 4.5 and 7.0. Xylanases of low molecular weight have great applicability in industrial processes, including paper bleaching and textile industry. Supported by: CAPES, CNPq, FAPDF, UFT.