Abstract
A novel endo-β-1,4-xylanase gene (xyn10C1) was cloned from Penicillium pinophilum C1 and overexpressed in Pichia pastoris. The 1071-bp full-length gene encodes a 356-residue polypeptide containing the catalytic domain of glycoside hydrolase 10. Deduced XYN10C1 shares highest amino acid sequence identity of 49.3% with a putative xylanase from Glomeella graminicola M1.001. Purified recombinant XYN10C1 showed maximal activity at pH 4.0–5.5 and 75°C, exhibited good adaptability to broad acidic pH and temperature ranges (>69.0% activity at pH 2.5–6.5; and >91.0% activity at 70–80°C and 22.2% even at 90°C), and was highly stable at pH 2.0–7.0 for 1h at 37°C. The specific activity, Km and Vmax values for birchwood xylan and soluble wheat arabinoxylan were 100.7 and 137.4U/mg, 4.3 and 6.9mg/ml, and 195.4 and 209.3μmol/min/mg, respectively. The enzyme was strongly resistant to most metal ions and proteases (pepsin and trypsin). Under simulated mashing conditions, addition of XYN10C1 (80U) to the brewery mash (12.5g in 50ml system) significantly increased the filtration rate by 26.7% and reduced the viscosity by 9.8%, respectively. All these favorable enzymatic properties make XYN10C1 attractive for potential applications in the food and animal feed industries.
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