A thermostable glucose oxidase from Aspergillus heteromophus CBS 117.55 with broad pH stability and digestive enzyme resistance

Abstract

In this study, the heterologous expression of an engineered thermostablle glucose oxidase from Aspergillus heteromophus CBS 117.55 was achieved in P. pastoris. This recombinant GoxAh was thermostable, with an optimal temperature range 25 °C-65 °C, and it was capable of retaining greater than 90% of its initial activity following a 10-min incubation at 75 °C. This enzyme had an optimum pH of 6.0, and it could retain above 80% of its initial activity following a 2-h incubation at a broad pH range (2.0–8.0). Moreover, GoxAh displayed excellent pepsin and trypsin resistance, and highly resistant to a range of tested metal ions and chemical reagents. These good properties make GoxAh a promising candidate for feed additive. The Km and kcat/Km values of GoxAh were 187 mM and 1.09/mM/s, which limited its widespread application to some degree. However, due to its excellent characteristics, GoxAh is still of potential economic value for high value-added areas, as well as a good initial enzyme for developing applicable feed enzyme by protein engineering.