Abstract
A bacterial test method was developed for detecting various DNA damaging agents by using the promoter-operator region of Escherichia coli SOS gene fused to the Vibrio harveyi luxAB genes. A E. coli strain containing the recA promoter-operator region (recApo)-luxAB fusion gene emitted light in a dose-dependent manner for the well-known DNA damaging agents mitomycin C (MMC), methyl methanesulfonate (MMS), and 4-nitroquinoline-1-oxide (4NQO). To make the response more sensitive, 4 base pairs of the recA operator sequence were changed, resulting in new promoter-operator sequence (po34) which had the consensus sequence for the LexA repressor binding. The E. coli strain containing po34-luxAB fusion gene showed 2-20 times higher sensitivity than the strain containing recApo-luxAB gene in the response to MMC, MMS, and 4NQO, because of its low background luminescence. As a comparison of the results of this method and the umu test for various compounds, the former had high sensitivity in 8 of the 14 samples compared with the latter.
