Expression of the xylanase Xyn11A in Pichia pastoris. PICXYN18 is the yeast strain transformed with the xyn11A cDNA in plasmid pPIC3.5. Control was transformed with pPIC3.5 vector alone. A) Xylan degradation halo produced on plates by the strain expressing Xyn11A. B) Xylanase activity in the culture supernatant of PICXYN18 (white square) or control (black square) strains, induced with methanol. C) SDS-PAGE of purified Xyn11A. D) SELDI-TOF spectrum for the purified Xyn11A showing the molecular weight (kDa) of the protein isoform in each peak.