title: Detection of Escherichia coli in drinking water using T7 bacteriophage-conjugated magnetic probe.
abstract: In this study, we demonstrate a bacteriophage (phage)-based magnetic separation scheme for the rapid detection of Escherichia coli (E. coli) in drinking water. T7 phage is a lytic phage with a broad host range specificity for E. coli. Our scheme was as follows: (1) T7 bacteriophage-conjugated magnetic beads were used to capture and separate E. coli BL21 from drinking water; (2) subsequent phage-mediated lysis was used to release endemic β-galactosidase (β-gal) from the bound bacterial cells; (3) the release of β-gal was detected using chlorophenol red-β-d-galactopyranoside (CRPG), a colorimetric substrate which changes from yellow to red in the presence of β-gal. Using this strategy, we were able to detect E. coli at a concentration of 1 × 10(4) CFU·mL(-1) within 2.5 h. The specificity of the proposed magnetic probes toward E. coli was demonstrated against a background of competing bacteria. By incorporating a pre-enrichment step in Luria-Bertani (LB) broth supplemented with isopropyl β-d-thiogalactopyranoside (IPTG), we were able to detect 10 CFU·mL(-1) in drinking water after 6 h of pre-enrichment. The colorimetric change can be determined either by visual observation or with a reader, allowing for a simple, rapid quantification of E. coli in resource-limited settings.
authors.affiliation: Department of Food Science, University of Massachusetts , 102 Holdsworth Way, Amherst, Massachusetts 01003, United States.
authors.forename: Juhong
authors.initials: J
authors.lastname: Chen
authors.affiliation: Department of Food Science, University of Massachusetts , 102 Holdsworth Way, Amherst, Massachusetts 01003, United States.
authors.forename: Samuel D
authors.initials: SD
authors.lastname: Alcaine
authors.affiliation: Department of Chemistry, University of Massachusetts , 710 North Pleasant Street, Amherst, Massachusetts 01003, United States.
authors.forename: Ziwen
authors.initials: Z
authors.lastname: Jiang
authors.affiliation: Department of Chemistry, University of Massachusetts , 710 North Pleasant Street, Amherst, Massachusetts 01003, United States.
authors.forename: Vincent M
authors.initials: VM
authors.lastname: Rotello
authors.affiliation: Department of Food Science, University of Massachusetts , 102 Holdsworth Way, Amherst, Massachusetts 01003, United States.
authors.forename: Sam R
authors.initials: SR
authors.lastname: Nugen
mesh_terms: D017123:Bacteriophage T7 / Q000737:chemistry*; D060766:Drinking Water / Q000382:microbiology*; D004926:Escherichia coli / Q000302:isolation & purification* / Q000821:virology*; D058185:Magnetite Nanoparticles / Q000737:chemistry*
chemical_list: D060766:Drinking Water; D058185:Magnetite Nanoparticles