Surface Display and Bioactivity of Bombyx mori Acetylcholinesterase on Pichia pastoris

A Pichia pastoris ( P. pastoris ) cell surface display system of Bombyx mori acetylcholinesterase ( Bm AChE) was constructed and its bioactivity was studied. The modified Bombyx mori acetylcholinesterase gene ( bmace ) was fused with the anchor protein ( AGα1) from Saccharomyces cerevisiae and transformed into P. pastoris strain GS115. The recombinant strain harboring the fusion gene bmace - AGα1 was induced to display Bm AChE on the P. pastoris cell surface. Fluorescence microscopy and flow cytometry assays revealed that the Bm AChE was successfully displayed on the cell surface of P. pastoris GS115. The enzyme activity of the displayed Bm AChE was detected by the Ellman method at 787.7 U/g (wet cell weight). In addition, bioactivity of the displayed Bm AChE was verified by inhibition tests conducted with eserine, and with carbamate and organophosphorus pesticides. The displayed Bm AChE had an IC 50 of 4.17×10 −8 M and was highly sensitive to eserine and five carbamate pesticides, as well as seven organophosphorus pesticides. Results suggest that the displayed Bm AChE had good bioactivity.