Characterization of a recombinant thermostable xylanase from deep-sea thermophilic Geobacillus sp MT-1 in East Pacific

A novel xylanase-producing thermophilic strain MT-1 was isolated from a deep-sea hydrothermal field in east Pacific. A xylanase gene encoding 331 amino-acid peptide from this isolate was cloned and expressed in Escherichia coli. The recombinant xylanase exhibited maximum activity at 70 degrees C and had an optimum pH of 7.0. It was active up to 90 degrees C and showed activity over a wide pH ranging from 5.5 to 10.0. The crude xylanase presented similar properties in temperature and pH to those of the recombinant xylanase. The recombinant xylanase was stable in 1 mM of enzyme inhibitors (PMSF, EDTA, 2-ME or DTT) and in 0.1% detergents (Tween 20, Chaps or Triton X-100), whereas, it was strongly inhibited by sodium dodecyl sulfate (SDS) (1 mM). In addition, its catalytic function was stable in the presence of Li+, Na+ or K+. However, it was strongly inhibited by Ni2+, Mn2+, Co2+, Cu2+, Zn2+, Cd2+, Hg2+ and Al3+ (1 or 0.1 mM). The K-m and V-max of the recombinant xylanase for oat spelt xylan were calculated to be 1.579 mg/ml and 289 mu mol/(min center dot mg), respectively. Our study, therefore, presented a rapid overexpression and purification of xylanase from deep-sea thermophile aimed at improving the enzyme yield for industrial applications and scientific research.