Purification and characterization of xylanase SRXL1 from Sporisorium reilianum grown in submerged and solid-state fermentation

Abstract

Sporisorium reilianum is a phytopathogenic fungus that produces the maize head smut. Hydrolytic enzymes such as xylanases have not been studied in this basidiomycete, although these enzymes are widely used within the industry. In this study, the characterization of a xylanase produced by S. reilianum grown in submerged and solid-state fermentation using different culture media was performed. Submerged fermentation with a medium containing birch xylan and yeast extract showed the highest xylanase activity (12.6 U/mL). The enzyme, purified through ion exchange chromatography, had a molecular weight of 42 kDa, as determined by SDS-PAGE, and a Km and Vmax of 1.72 mg/mL and 2.48 μmol/mL/min, respectively. The optimal values of pH and temperature were 5.0 and 70 °C, respectively. The enzyme showed activity over a broad range of temperatures and pHs. Zn2+, Fe3+, and Mn2+ ions increased xylanase activity. Sequence protein analysis showed 100% similarity with the theoretical protein encoded by the sr14403 gene of S. reilianum, encoding a putative endo-β-1,4-xylanase. This is the first report on the production and purification of a xylanase from this fungus, which has interesting biochemical characteristics for application in biotechnological processes.