T7 bacteriophages (phages) have been genetically engineered to carry the lacZ operon, enabling the overexpression of beta-galactosidase (β-gal) during phage infection and allowing for the enhanced colorimetric detection of Escherichia coli (E. coli). Following the phage infection of E. coli, the enzymatic activity of the released β-gal was monitored using a colorimetric substrate. Compared with a control T7 phage, our T7lacZ phage generated significantly higher levels of β-gal expression following phage infection, enabling a lower limit of detection for E. coli cells. Using this engineered T7lacZ phage, we were able to detect E. coli cells at 10 CFU·mL-1 within 7 h. Furthermore, we demonstrated the potential for phage-based sensing of bacteria antibiotic resistance profiling using our T7lacZ phage, and subsequent β-gal expression to detect antibiotic resistant profile of E. coli strains.
Keywords: antibiotic resistance profiling; bacteria detection; beta-galactosidase; colorimetry; engineered bacteriophages.