Development of a Whole-Cell Biocatalyst/Biosensor
by Display of Multiple Heterologous Proteins on the Escherichia coli Cell Surface for the Detoxification
and Detection of Organophosphates
- Publication date
- Publisher
Abstract
This
paper reports the codisplay of organophosphorus hydrolase
(OPH) and methyl parathion hydrolase (MPH)–green fluorescent
protein (GFP) fusion on the cell surface of Escherichia
coli using the truncated ice nucleation protein (INPNC)
and Lpp–OmpA as the anchoring motifs. The surface localization
of both OPH and MPH–GFP was demonstrated by cell fractionation,
Western blot analysis, protease accessibility experiment, and immunofluorescence
microscopy. Anchorage of the foreign proteins on the outer membrane
neither inhibits cell growth nor affects cell viability. The recombinant
strain can be used as a whole-cell biocatalyst and showed a broader
substrate range than strains expressing either OPH or MPH. A mixture
of six organophosphorus pesticides (OPs) (0.2 mM each) could be degraded
completely within 5 h. The broader substrate specificity in combination
with the rapid degradation rate makes the recombinant strain a promising
candidate for detoxification of OPs. The fluorescence of surface-displayed
GFP is very sensitive to environmental pH change. Because hydrolysis
of OPs by OPH or MPH generates protons, the recombinant <i>E.
coli</i> could be used as a whole-cell biosensor for the rapid
detection of OPs by evaluating fluorescence changes as a function
of OP concentrations