Quantification of Escherichia Coli via Analysis of β-glucuronidase Enzyme Concentrations

Abstract

Concentration of Escherichia coli can be quantified based on a digestive enzyme produced by 97% of E. coli strains called β-glucuronidase (β-GUS). When in contact with a β-glucuronide (β-GLU) molecule, the enzyme cleaves the β-GLU segment off the molecule, leaving the remaining fragment untouched. The remaining fragment can serve as a marker for the presence of the enzyme and can be quantifiably calibrated to determine the concentration of the E. coli in each sample. For a colourimetric method approach, 4-nitrophenol-β-D-glucuronide (4-NβDg) can be used as a dye for the enzyme. The remainder of the molecule after enzymatic cleavage is a 4-nitrophenol, which is blue in colour. The change in colour can be quantified based on a calibration curve. For an electrochemical method approach, 4-NβDg can also be used because 4-nitrophenol gives a characteristic cyclic voltammogram on a potentiostat. The change in resistance of 4-nitrophenol can be determined and calibrated to show the concentration of the E. coli in each sample. This research is ongoing and does not have the finalized results on the outcome of the work described above.

Discipline: Chemistry

Faculty Mentor: Dr. Sam Mugo