Genetically modified Escherichia coli for colorimetric detection of inorganic and organic Hg compounds.
A sensitive colorimetric bacterial system was developed for the detection of Hg(II) and organomercury compounds. The bioactive species, a recombinant Escherichia coli, produces proportionally elevated levels of the enzyme beta-galactosidase with increasing amounts of Hg. This is due to a reporter plasmid which carriers a Hg(II)-inducible promoter (mer promoter) from the Hg resistance transposon Tn501 regulating the transcription of a promoterless lacZ gene. Additionally, a pMB1 origin of replication without the natural RNA polymerase start site is fused downstream of the mer promoter leading to a Hg(II)-inducible plasmid replication, which results in an improved signal-to-noise ratio. To enhance the sensitivity of this cellular biosensor, the transport proteins for Hg(II) uptake are constitutively produced by a helper plasmid. To enable the detection of organically bound Hg, the Streptomyces lividans organomercurical lyase, an enzyme which catalyses the cleavage of C-Hg-bonds of organomercurial compounds, is also provided by the helper plasmid. Hg(II) and phenylmercuric acetate (PMA) concentrations as low as 5 x 10(-10) M (0.1 ppb) may be detected within a few minutes.
Klein
J
J
Institute of Industrial Genetics, University of Stuttgart, Germany.
Altenbuchner
J
J
Mattes
R
R
D001692:Biological Transport; D003124:Colorimetry; D004587:Electrophoresis, Agar Gel; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D005798:Genes, Bacterial / Q000235:genetics; D017930:Genes, Reporter / Q000235:genetics; D007763:Lac Operon / Q000235:genetics; D017669:Mercury Compounds / Q000032:analysis* / Q000378:metabolism / Q000633:toxicity; D010957:Plasmids / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism
D017669:Mercury Compounds; D001616:beta-Galactosidase