Green fluorescent protein-based biosensor for detecting SOS-inducing activity of genotoxic compounds

Increasing levels of environmental pollution demand specific and sensitive methods for detection of genotoxic agents in water, food products and environmental samples. Tests for genotoxicity assessment are often based on biosensor strains that respond to DNA damage induced by chemicals. In the present study, fluorescent reporter Escherichia coli strains have been developed, which contain a plasmid-borne transcriptional fusion between the DNA-damage inducible recA promoter and the green fluorescent protein gene (gfp) or a gene encoding a red-shifted, higher intensity GFP variant (mutant 3). GFP-based biosensors allowed the detection of a dose-dependent response to genotoxic agents such as mitomycin C (MMC), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and nalidixic acid (NA). A reporter strain carrying recA'-gfp mutant 3 fusion gave more dramatic and sensitive response than a strain containing the wild-type gfp. These results indicate that recA'-gfp mutant 3-based biosensor is potentially useful for detection of genotoxins.