Strongly enhanced bacterial bioluminescence with the operon for single-cell imaging.

Bioluminescence imaging of single cells is often complicated by the requirement of exogenous luciferins that can be poorly cell-permeable or produce high background signal. Bacterial bioluminescence is unique in that it uses reduced flavin mononucleotide as a luciferin, which is abundant in all cells, making this system purely genetically encodable by the operon. Unfortunately, the use of bacterial bioluminescence has been limited by its low brightness compared with other luciferases. Here, we report the generation of an improved operon named with an approximately sevenfold increased brightness when expressed in ; can be used to image single cells with enhanced spatiotemporal resolution over several days. In addition, since only metabolically active cells produce bioluminescent signal, we show that can be used to observe the effect of different antibiotics on cell viability on the single-cell level.