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 Phi V10 was modified to express NanoLuc luciferase (Nluc) derived from the deep-sea shrimp Oplophorus gracilirostris. Once infected by the Phi V10 reporter phage, E. coli O157: H7 produces a strong bioluminescent signal upon addition of commercial luciferin (Nano-Glo (R)). Enrichment assays using E. coli O157: H7 grown in LB broth with a reporter phage concentration of 1.76 x 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 x 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.