An Engineered Reporter Phage for the Fluorometric Detection of <i>Escherichia coli</i> in Ground Beef

• Main Authors: Anqi Chen, Danhui Wang, Sam R. Nugen, Juhong Chen
• Format: Article
• Language: English
• Published: MDPI AG 2021-02-01
• Series: Microorganisms
• Subjects: bacteria detection; engineered bacteriophages; fluorescent assay; beta-galactosidase; ground beef
• Online Access: https://www.mdpi.com/2076-2607/9/2/436

Despite 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-d-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.