High-level expression of a xylanase gene from the thermophilic fungus Paecilomyces thermophila in Pichia pastoris.

A xylanase gene from Paecilomyces thermophila was functionally expressed in Pichia pastoris. The recombinant xylanase (xynA) was predominantly extracellular; in a 5 l fermentor culture, the total extracellular protein was 8.1 g l−1 with an activity of 52,940 U ml−1. The enzyme was purified to homogeneity with a recovery of 48 %. The recombinant xynA was optimally active at 75 °C, as measured over 10 min, and at pH 7. The enzyme was stable up to 80 °C for 30 min. It hydrolyzed birchwood xylan, beechwood xylan and xylooligosaccharides to produce xylobiose and xylotriose as the main products.