Overexpression and characterization of a thermostable trehalose synthase from Meiothermus ruber

A thermostable trehalose synthase (TreS) gene from Meiothermus ruber CBS-01 was cloned and overexpressed in Escherichia coli. The purified recombinant TreS could utilize maltose to produce trehalose, and showed an optimum pH and temperature of 6.5 and 50 degrees C, respectively. Kinetic analysis showed that the enzyme had a twofold higher catalytic efficiency (k (cat)/K (m)) for maltose than for trehalose, indicating maltose as the preferred substrate. The TreS also had a weak hydrolytic property with glucose as the byproduct, and glucose was a strong competitive inhibitor of the enzyme. The maximum production of trehalose by the enzyme reached 65% at 20 degrees C. The most importantly the enzyme could maintain very high activity (above 90%) at pH 4.0-8.0 and 60 degrees C 5 h. These results provided that the stable TreS was suitable for the industrial production of trehalose from maltose in a one-step reaction.