Développement d'un biocapteur bactérien pour la détection de métaux lourds

Abstract : By screening a library of lacZ transcriptional gene fusions in Escherichia coli on HgCl2, a gene whose expression was found to be mercury-inducible was isolated. This gene, named zntA, encodes a metal translocating P-type ATPbase conferring resistance of E. coli to cadmium, lead and zinc by extrusion. By measuring zntA::lacZ gene expression, we have shown that this fusion is responsive to the presence of inorganic compounds of cadmium, mercury, lead ans zinc in a dose-dependant manner. A zntA-based reporter plasmid has been constructed by insertion of the PCR synthesized promotor sequence of zntA into the plasmid vector containing luxCDABE genes encoding bacterial luciferase of Vibrio fischeri.The resulting plasmid, pZNT::lux, conferred light production to different E. coli strains upon exposure to heavy metals. The obtained reporter strain was used to develop a whole cell biosensor system for the detection of heavy metals by measuring light emission. The test conditions have been optimized by the modification of parameters such as culture medium, bacterial growth phase, cell density and pH, and the resulting protocol allowed the rapid detection of cadmium, mercury, lead and zinc from thresholds of 0,01 µM, 0,1µM, and 0,3 µM repectively. The main interest of this analytical tool is the evaluation of bioavailable heavy metal content in an environmental sample. Preliminary probing for the bioavailable heavy metals in complex matrixes such as soils and their leachates was successful. Though various environmental factors may influence the luminescence response, and the presence of different heavy metals may not be distinguished, this technique presents an interesting analytical tool for a semi-quantitative measure of heavy metals in environmental samples
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Karl Bernhard Riether. Développement d'un biocapteur bactérien pour la détection de métaux lourds. Sciences agricoles. Université Paul Verlaine - Metz, 2001. Français. ⟨NNT : 2001METZ019S⟩. ⟨tel-01748961⟩

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