| Popis: |
In this study, we developed two new whole-cell biocatalysts by immobilizing aminopeptidase (Aps) on the surface of yeast cells, using N-terminal fusion and C-terminal fusion through lectin mediated display system. After the two strains were cultured in the medium with galactose as inducer for 48 hours, the activity of expressing Aps was at a high level of 0.25 U/OD600/mL and 0.12 U/OD600/mL. The correct location of Aps was confirmed by immunofluorescence analysis and flow cytometry. Afterwards two whole cell catalysts could be reused with high stability as it retained more than 70% of initial activity after ten repeated batch reactions. Using β-cypermethrin (β-CP) as a substrate, the effectiveness of two new whole-cell catalysts in the treatment of highly hydrophobic organic pollutants was evaluated. The results showed that when the concentration of β-CP was 200 mg·L , the hydrolysis rates of the two whole cell catalysts were 33.16 μmol·L ·day and 28.99 μmol·L ·day , and has the ability to degrade a variety of pyrethroid pesticides. The β-CP residue in lettuce and cherry tomatoes could be removed more than 70% under the conditions of the Aga2N-Aps whole cell catalyst preparation dilution of 100 times. This is the first report on the development of surface display Aps biocatalyst, which can be used as an effective and renewable alternative for the treatment of highly hydrophobic organic pollutants. |
