Aspergillus sp. 2M1 Xylanase: Production, Characterization and Application in the Pulp and Paper Industry

Abstract

Aspergillus sp. 2M1 produces high levels of β -xylanases and β-xylosidases. Different carbon sources as inductors of xylanases were used. Production of xylanases were evaluated in a combined packed-bed/air-lift bioreactor (PBAL) in free and immobilized form and with a stationary tray bioreactor (STB). In the free form, xylanase activity was similar to that in Erlenmeyer flasks, but in the immobilized form higher values were observed Similar xylanases activities with the STB were found In order to understand xylanases stabilities, chemical modifications were done. Among others, 1-ethyl-3(3-dimethyl aminopropyl) carbodiimide (EDC) affected the xylanase activity. On the basis of this study, it was concluded that one or more carboxyl groups are in the active site of the xylanase from Aspergillus sp. 2M1. Xylanases induced by oatt birch and pinus xylans exhibited their optimum pH at 5.5 and at 55°C. At this temperature the half-lives of the xylanase activities were 11.8, 7.2 and 4.4 min for pinus, birch and oat, respectively. Xylanases induced by birch xylan were applied for a pre-bleaching experiment. Pre-bleaching of pinus Kraf pulp followed by a short oxygen-peroxide sequence, resulted in a very high selectivity as compared with commercial xylanases.