Cloning and characterization of a novel mesophilic xylanase gene Fgxyn3 from Fusarium graminearum Z-1

In order to search for high specific activity and the resistant xylanases to XIP-I and provide more alternative xylanases for industrial production, a strain of Fusarium graminearum from Triticum aestivum grains infected with filamentous fungus produced xylanases was isolated and identified. Three xylanase genes from Fusarium graminearum Z-1 were cloned and successfully expressed in E. coli and P. pastoris, respectively. The specific activities of Fgxyn1, _EFgxyn2 and _EFgxyn3 for birchwood xylan were 38.79, 0.85 and 243.83 U/mg in E. coli, and 40.11, 0 and 910.37 U/mg in P. pastoris, respectively. _EFgxyn3 and _PFgxyn3 had the similar optimum pH at 6.0 and pH stability at 5.0–9.0. However, they had different optimum temperature and thermal stability, with 30 °C for _EFgxyn3 and 40 °C for _PFgxyn3, and 4–35 °C for _EFgxyn3 and 4–40 °C for _PFgxyn3, respectively. The substrate spectrum and the kinetic parameters showed that the two xylanases also exhibited the highest xylanase activity and catalytic efficiency (k_cat/k_m) toward birchwood xylan, with 243.83 U/mg and 61.44 mL/mg/s for _EFgxyn3 and 910.37 U/mg and 910.37 mL/mg/s for _PFgxyn3, respectively. This study provided a novel mesophilic xylanase with high specific activity and catalytic efficiency, thus making it a promising candidate for extensive applications in animal feed and food industry.