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EN
Recently, we have developed a novel assay designed for detection of mutagenic pollution of the marine environment. This assay is based on the use of a series of genetically modified strains (named BB7, BB7M, BB7X and BB7XM) of a marine bacterium Vibrio harveyi. Sensitivity of the V. harveyi mutagenicity assay was found to be similar to, or even somewhat higher than, that of the commonly used Ames test. Subsequent studies indicated that this assay may be useful in assessment of mutagenic contamination of the marine environment. Nevertheless, we assumed that improvement of this assay is still possible, and thus we aimed to optimise its procedures. Here we present our research on the optimisation of the V. harveyi mutagenicity assay, which indicated that different tester strains used in this assay give the best results depending upon the experimental conditions employed. Incubation of bacteria in a buffer, rather than in a nutrient broth, containing a mutagen, increased the efficiency of the assay with BB7 and BB7M strains, but had a deleterious effect in the case of BB7X and BB7XM. The latter couple of strains revealed higher mutagenicity in the plate assay, as compared to the liquid medium assay. However, the opposite effect was observed for BB7 and BB7M. Low-dose (1 J m?2) UV irradiation, as well as 30 min incubation in 0.1 M CaCl2, had no significant effect on the efficiency of the assay when using BB7 and BB7M, whereas the number of mutagen-induced mutants of BB7X and BB7XM strains increased about two times under these conditions. Our previous experiments indicated that various tester strains revealed different sensitivity to particular mutagens. Thus, a series of strains should be used in the assay. Results presented in this report show that different conditions should be used for two pairs of the tester strains: BB7 and BB7M, and BB7X and BB7XM.
EN
Mutagenic pollution of the natural environment is currently one of the most serious environmental problems. It includes the pollution of marine sediments. Therefore, rapid detection of the presence of mutagens is an important issue. Recently, we have developed a novel microbiological assay for rapid assessment of mutagenicity of samples from the natural environment. This assay is based on bioluminescence of a mutant Vibrio harveyi strain, and was shown to be useful in testing samples of marine water and plant tissues. Here we demonstrate the usefulness of this assay in preliminary assessment of mutagenic pollution of marine sediments. Mutagenicity of environmental samples taken from the Baltic Sea, is documented and compared here with a commercially available standard sediment sample (IAEA 383), which contains known amounts of mutagenic compounds. The whole procedure, from obtaining a sample in the laboratory to getting final results, is very short (less than 4 h).
EN
Intensity of light emission by luminescent bacteria in response to UV irradiation and chemical mutagens was tested. We demonstrated that luminescence of six strains of marine bacteria (belonging to four species: Photobacterium leiognathi, P. phosphoreum, Vibrio fischeri and V. harveyi) is significantly increased by UV irradiation relatively shortly after dilution of cultures. Such a stimulation of luminescence was abolished in cells treated with chloramphenicol 15 min before UV irradiation, indicating that effective gene expression is necessary for UV-mediated induction of light emission. These results suggest that stimulation of luminescence in UV-irradiated bacterial cells may operate independently of the quorum sensing regulation. A significant induction of luminescence was also observed upon treatment of diluted cultures of all investigated strains with chemical mutagens: sodium azide (SA), 2-methoxy-6-chloro-9-(3-(2-chloroethyl)aminopropylamino)acridine ? 2HCl (ICR-191), 4-nitro-o-phenylenediamine (NPD), 4-nitroquinolone-N-oxide (NQNO), 2-aminofluorene (2-AF), and benzo[?]pyrene. These results support the proposal that genes involved in bioluminescence belong to the SOS regulon. The use of bacterial luminescence systems in assays for detection of mutagenic compounds is discussed in the light of this proposal.
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