A comparative study of maltooligosyltrehalose synthase from Sulfolobus acidocaldarius expressed in Pichia pastoris and Escherichia coli

Two genes encoding the maltooligosyltrehalose synthase (MTSase) from Sulfolobus acidocaldarius ATCC 33909 were synthesized: one (designated E-treY) using codons preferred by Escherichia coli and the other (designated P-treY) using codons preferred by Pichia pastoris. E-treY was inserted into pET-24a(+), and the resulting plasmid was used to transform E. coli BL21(DE3). P-treY was inserted into pPIC3.5 K and pGAPZA, and the resulting plasmids were used to transform P. pastoris KM71. The maximum MTSase activity expressed by these E. coli and P. pastoris strains reached 31.6 and 133.0 U mL−1, respectively. The purified MTSases displayed the same pH (pH 5.5) and temperature (75 °C) optima. Both had a half-life of 12 h at 75 °C. The recombinant P. pastoris KM71/pPIC3.5K-treY strain producing the highest enzyme activity was used to optimize the fermentation conditions in a 3.6-L bioreactor. Fermentation for 96 h under optimal conditions yielded an MTSase activity of 747.4 U mL−1.