Isolation and characterization of glucoamylase from a wastewater treatment yeast Hansenula fabianii J640, and construction of expression vector.

Hansenula fabianii J640 highly expresses an extracellular glucoamylase (GA). Here, we purified the GA and showed that it has pH and temperature optima of 5.0 and 50 °C, respectively, stable at temperatures up to 50 °C, and is inhibited by Ag(2+), Hg(2+), and Cu(2+). The gene was found in an expression library with anti-GA antibodies. A cDNA was found to encode 491 amino acids, including a putative signal peptide of 21 amino acids. Because of the gene's high expression, we used its promoter and terminator regions to improve a previously developed H. fabianii J640 expression system.