Supplementary Material for: Molecular Cloning, Overexpression and Characterization of a Novel Feruloyl Esterase from a Soil Metagenomic Library

2011-07-12T00:00:00Z (GMT) by Sang S.L. Li G. Hu X.P. Liu Y.H.
The gene <i>estF27</i>, encoding a protein with feruloyl esterase activity, was cloned through functional screening from a soil metagenomic library and expressed in <i>Escherichia</i><i>coli</i> BL21 (DE3) with high solubility. Sequence analysis showed that <i>estF27</i> encoded a protein of 291 amino acids with a predicted molecular mass of 31.16 kDa. According to the substrate specificity, EstF27 was classified as a type A feruloyl esterase. EstF27 displayed optimal activity at 40°C and pH 6.8. This enzyme was stable in a broad pH range of 5.0–10.0 over 24 h, and retained more than 50% of its activity after 96 or 120 h incubation in the presence of 3 <i>M</i> KCl or 5 <i>M</i> NaCl. The enzyme activity was slightly enhanced by the addition of Mg<sup>2+</sup> and Fe<sup>3+</sup> at a low concentration, and completely inhibited by Cu<sup>2+</sup>. In the enzymatic hydrolysis of destarched wheat bran, EstF27 could release ferulic acid from it in the presence of xylanase from <i>Thermomyces lanuginosus</i>. Given its alkalitolerance, halotolerance and highly soluble expression, EstF27 is a promising candidate for industrial applications.