The Use of a Novel NanoLuc -Based Reporter Phage for the Detection of Escherichia coli O157:H7

Rapid detection of the foodborne pathogen Escherichia coli O157:H7 is of vital importance for public health worldwide. Among detection methods, reporter phages represent unique and sensitive tools for the detection of E. coli O157:H7 from food as they are host-specific and able to differentiate live cells from dead ones. Upon infection, target bacteria become identifiable since reporter genes are expressed from the engineered phage genome. The E. coli O157:H7 bacteriophage ΦV10 was modified to express NanoLuc luciferase (Nluc) derived from the deep-sea shrimp Oplophorus gracilirostris . Once infected by the ΦV10 reporter phage, E. coli O157:H7 produces a strong bioluminescent signal upon addition of commercial luciferin (Nano-Glo ® ). Enrichment assays using E. coli O157:H7 grown in LB broth with a reporter phage concentration of 1.76 × 10 2 pfu ml −1 are capable of detecting approximately 5 CFU in 7 hours. Comparable detection was achieved within 9 hours using 9.23 × 10 3 pfu ml −1 of phage in selective culture enrichments of ground beef as a representative food matrix. Therefore we conclude that this NanoLuc reporter phage assay shows promise for detection of E. coli O157:H7 from food in a simple, fast and sensitive manner.