Purification and partial characterisation of a thermostable xylanase from salt-tolerant Thermobifida halotolerans YIM 90462 T

ThxynA, an extracellular xylanase of T. halotolerans YIM 90462(T), was purified to homogeneity from a fermentation broth by ultra-filtration, ammonium sulphate precipitation, hydrophobic chromatography and ion exchange chromatography. The purified xylanase has a molecular mass of 24 kDa and is optimally active at 80 degrees C and pH 6.0. The enzyme is stable over a broad pH range (pH 6.0-10.0) and shows good thermal stability when incubated at 70 degrees C for 1 h. The K-m and V-max values of the enzyme are 11.6 mg/mL and 434 mu mol mg(-1) min(-1), respectively, using oat spelt xylan as a substrate. Moreover, the enzyme seemingly has both xylanase activity and cellulase activity. These unique properties suggest that it may be useful for industrial applications. (C) 2011 Elsevier Ltd. All rights reserved.