The discovery and characterizatton of c&acting promoter regions and transacting regulatory proteins is often aided by use of reporter gene fusions In bacterial systems, frequently used reporters include 1acZ (β-galactostdase), phoA (alkaline phosphatase), cam (chloramphemcol transacetylase), and lux (bacterial luciferase). Among these, the lux reporter is distinct, because the reporter genes’ ultimate product, light, can be measured without disrupting the cell. Furthermore, utthzatton of the five-gene 1uxCDABE reporter system allows continuous monitoring of light production, An additional advantage of the lux reporter is the sensitivity and large dynamic range of light detection equipment, which enables very weak to very strong transcripttonal acttvtty to be measured.