Reporter genes that permit facile detection of promoter activity are of central importance to molecular genetic research. One especially useful transcriptional reporter is the luxCDABE operon which encodes both luciferase (a heterodimer of LuxA and LuxB) and enzymes required for the production of its substrate tetradecanal (LuxC, LuxD and LuxE). The biochemical requirements for the production of light by these gene products are available in the cytoplasm of all aerobically growing organisms, so cells that express the luxCDABE operon emit light spontaneously