Photographic detection of luminescence in Escherichia coli containing the gene for firefly luciferase.

The gene for firefly luciferase (luc) can be used as a generalized genetic probe. A method that aids in the analysis of shuttle vectors containing luc by allowing verification in Escherichia coli of a functional coding sequence is presented here. Colonies containing a functional form of luc are detected on film after luciferin is added to initiate the luminescent reaction. Two conditions, lowering the pH of the environment and maintaining aerobic conditions, were found to greatly improve the sensitivity of the assay. This technique may be useful in the development of genetic constructs that alter the natural coding sequence of luc, such as in gene fusions.