High level expression of a recombinant xylanase by Pichia pastoris cultured in a bioreactor with methanol as the sole carbon source: Purification and biochemical characterization of the enzyme

•Xyn11A gene was expressed in Pichia pastoris X-33 under the AOX1 promoter.•Fed-batch fermentation with methanol as sole carbon source was followed.•Minimal salt medium was used to reduce costs in bioreactor fermentation.•High level production of Xyn11AAOX1 in bioreactor was achieved.•Xyn11AAOX was purified in one-step and biochemically characterized.