Cloning, over-expression and characterization of a thermo-tolerant xylanase from Thermotoga thermarum

The xyn10B gene, encoding the endo-1,4-β-xylanase Xyn10B from Thermotoga thermarum, was cloned and expressed in Escherichia coli. The ORF of the xyn10B was 1,095 bp and encoded to mature peptide of 344 amino acids with a calculated MW of 40,531 Da. The recombinant xylanase was optimally active at 80 °C, pH 6.0 and retained approx. 60 % of its activity after 2 h at 75 °C. Apparent K m , k cat and k cat /K m values of the xylanase for beechwood xylan were 1.8 mg ml(-1), 520 s(-1) and 289 ml mg(-1) s(-1), respectively. The end products of the hydrolysis of beechwood xylan were mainly oligosaccharides but without xylose after 2 h hydrolysis.