Secretive expression of bacterial β-xylosidase gene including hexahistidin-tag in Pichia pastoris

 Introduction: β-D-Xylosidases (EC 3.2.1.37), one of the most important hemicellulases with high potential industrial application such as bioethanol production, are exo-type glycosidases that catalyze the successive removal of β-xylosyl residues from the non-reducing termini of xylobiose and higher linear β-1,4-xylooligosaccharides and in conjunction with β-xylanases are essential in completely depolymerizing xylan. The aim of this study was secretive expression of bacterial β-xylosidase gene including hexahistidin-tag in Pichia pastoris in order to achieve high level expression and enzyme purification subsequently.  Materials and Methods: In this study, after optimizing the sequence of protein encoding bacterial β-xylosidase based on the expression codon usage of Pichia pastoris and addition of 6xHis-tag sequence through suitable designed primers to gene, transformation of recombinant plasmids was performed through electroporation method into the expression yeast. Results: The results showed that the recombinant β-xylosidase production was 40 U/L with 0/6 U/mg specific activity in flask culture.  Conclusion: Cloning and successful expression of bacterial β-xylosidase gene was carried out in order to obtain an active and stable enzyme with high level expression from yeast expression system