Table 1. Reporter genes used for detection of foodborne pathogens by engineered reporter phages.

Gene	Encoded product	Advantages	Disadvantages	Refs.
luxCDABE	complete bacterial luciferase operon (encodes luciferase holoenzyme LuxAB and proteins providing its aldehyde substrate)	• high sensitivity • high signal-to-noise ratio (low luminescence background in food samples) • no substrate addition required	• packaging constraints (large DNA fragment) • relatively weak luminescence signal	55
luxAB	bacterial luciferase genes encoding the two subunits of the holoenzyme LuxAB	• high sensitivity • high signal-to-noise ratio (low luminescence background in food samples) • smaller than the luxCDABE operon	• addition of substrate required • transient luminescence signal	56, 57
luxI	Quorum sensing; LuxI generates the autoinducer AHL, which stimulates transcription of luxCDABE	• high sensitivity • no substrate addition required • smaller compared with luxCDABE • longer signal emission due to presence of bioreporter cells	• bioreporter strain carrying luxCDABE required • false-positive results possible (bioreporter luminescence can be induced by compatible autoinducers present in the environment)	58
luc	firefly luciferase Luc	• high sensitivity • high signal-to-noise ratio (low luminescence background in food samples	• addition of substrate required • substrate expensive • short luminescence signal	59
inaW	INP	• very high sensitivity • high signal-to-noise ratio • no specialized equipment required	• addition of phase-sensitive fluorescent dye required • target cell must present INP on its surface	60
lacZ	β-galactosidase enzyme	• No specialized equipment needed • works with various substrates (colorimetric, fluorescent, luminescent)	• addition of substrate required • high background of β-galactosidase activity in the environment	61
gfp	GFP	• no substrate addition required • long-lasting signal increasing over time • multiplexed detection possible when different fluorescent markers are used • high stability and low toxicity	• posttranslational chromophore formation required • low signal-to-noise ratio due to background fluorescence • detection by fluorescence microscopy or FACS requires expensive equipment and trained personnel	62
celB	Pyrococcus furiosus thermostable β-glycosidase CelB	• thermostable enzyme: elimination of background enzyme activity possible by heating, resulting in high signal-to-noise ratio • works with various substrates (colorimetric, fluorescent, luminescent) • long-lasting signal increasing over time	• addition of substrate required	63
biotinylation tag coding sequence (used in combination with QDs)	25 amino acid biotinylation peptide	• small reporter gene (75 bp) • when used with QDs: very high sensitivity due to superior optical properties • multiplexed assays possible	• addition of functionalized QDs required • detection by fluorescence microscopy or FACS requires expensive equipment and trained personnel	64
tetracysteine tag coding sequence	12 amino acid tetracysteine peptide	• very small reporter gene (36 bp)	• addition of dye required • detection by fluorescence microscopy or FACS requires expensive equipment and trained personnel	65