title: Electrochemical Detection of Escherichia coli from Aqueous Samples Using Engineered Phages.
abstract: In this study, an enzyme-based electrochemical method was developed for the detection of Escherichia coli (E. coli) using the T7 bacteriophages engineered with lacZ operon encoding for beta-galactosidase (β-gal). The T7lacZphages can infect E. coli, and have the ability to trigger the overexpression of β-gal during the infection of E. coli. The use of the engineered phages resulted in a more sensitive detection of E. coli by (1) overexpression of β-gal in E. coli during the specific infection and (2) release of the endogenous intracellular β-gal from E. coli following infection. The endogenous and phage-induced β-gal was detected using the electrochemical method with 4-aminophenyl-β-galactopyranoside (PAPG) as a substrate. The β-gal catalyzed PAPG to an electroactive species p-aminophenol (PAP) which could be monitored on an electrode. The electrochemical signal was proportional to the concentration of E. coli in the original sample. We demonstrated the application of our strategy in aqueous samples (drinking water, apple juice, and skim milk). Using this method, we were able to detect E. coli at the concentration of approximately 105CFU/mL in these aqueous samples in 3 h and 102CFU/mL after 7 h. This strategy has the potential to be extended to detect different bacteria using specific bacteriophages engineered with gene encoding for appropriate enzymes.
authors.affiliation: Department of Food Science, University of Massachusetts , Amherst, Massachusetts 01003, United States.|Department of Food Science, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Danhui
authors.identifier: 0000-0002-3855-4733
authors.initials: D
authors.lastname: Wang
authors.affiliation: Department of Food Science, University of Massachusetts , Amherst, Massachusetts 01003, United States.|Department of Food Science, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Juhong
authors.identifier: 0000-0002-6484-2739
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Food Science, University of Massachusetts , Amherst, Massachusetts 01003, United States.|Department of Food Science, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Sam R
authors.identifier: 0000-0003-3638-1776
authors.initials: SR
authors.lastname: Nugen
mesh_terms: D000627:Aminophenols / Q000737:chemistry / Q000378:metabolism; D001435:Bacteriophages / Q000235:genetics*; D001628:Beverages / Q000382:microbiology; D055664:Electrochemical Techniques; D004566:Electrodes; D004926:Escherichia coli / Q000201:enzymology / Q000302:isolation & purification*; D005697:Galactosides / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D014871:Water Microbiology; D001616:beta-Galactosidase / Q000235:genetics
chemical_list: D000627:Aminophenols; D005697:Galactosides; C010677:4-aminophenyl-beta-galactoside; D001616:beta-Galactosidase; C026729:4-aminophenol