Chen, AnqiWang, DanhuiNugen, Sam R.Chen, Juhong2021-02-262021-02-262021-02-19Chen, A.; Wang, D.; Nugen, S.R.; Chen, J. An Engineered Reporter Phage for the Fluorometric Detection of Escherichia coli in Ground Beef. Microorganisms 2021, 9, 436.http://hdl.handle.net/10919/102457Despite enhanced sanitation implementations, foodborne bacterial pathogens still remain a major threat to public health and generate high costs for the food industry. Reporter bacteriophage (phage) systems have been regarded as a powerful technology for diagnostic assays for their extraordinary specificity to target cells and cost-effectiveness. Our study introduced an enzyme-based fluorescent assay for detecting the presence of <i>E. coli</i> using the T7 phage engineered with the <i>lacZ</i> operon which encodes beta-galactosidase (β-gal). Both endogenous and overexpressed β-gal expression was monitored using a fluorescent-based method with 4-methylumbelliferyl β-<span style="font-variant: small-caps;">d</span>-galactopyranoside (MUG) as the substrate. The infection of <i>E. coli</i> with engineered phages resulted in a detection limit of 10 CFU/mL in ground beef juice after 7 h of incubation. In this study, we demonstrated that the overexpression of β-gal coupled with a fluorogenic substrate can provide a straightforward and sensitive approach to detect the potential biological contamination in food samples. The results also suggested that this system can be applied to detect <i>E. coli</i> strains isolated from environmental samples, indicating a broader range of bacterial detection.application/pdfenCreative Commons Attribution 4.0 Internationalbacteria detectionengineered bacteriophagesfluorescent assaybeta-galactosidaseground beefArticle - Refereed2021-02-26https://doi.org/10.3390/microorganisms9020436