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

ThxynA, an extracellular xylanase of T. halotolerans YIM 90462T, 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 °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 °C for 1 h. The Km and Vmax values of the enzyme are 11.6 mg/mL and 434 μmol 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.

► The stain we used can grow in a high temperature and a high saline condition.
► The enzyme showed high thermal stability, even incubated in 70 °C for 1 h.
► The enzyme was stable over a broad pH range from 6.0 to 10.0.
► It has a potential in the treatment of heavy metal wastewater for its Pb2+ tolerance.
► The enzyme seemingly has both xylanase activity and cellulase activity.