title: Cell-density-dependent sensitivity of a mer-lux bioassay.
abstract: The sensitivity of a previously described assay (O. Selifonova, R. Burlage, and T. Barkay, Appl. Environ. Microbiol. 59:3083-3090, 1993) for the detection of bioavailable inorganic mercury (Hg2+) by the activation of a mer-lux fusion was increased from nanomolar to picomolar concentrations by reducing biomass in the assays from 10(7) to 10(5) cells ml-1. The increase in sensitivity was due to a reduction in the number of cellular binding sites that may compete with the regulatory protein, MerR, for binding of the inducer, Hg2+. These results show that (i) the sensitivity of the mer-lux assay is sufficient for the detection of Hg2+ in most contaminated natural waters and (ii) mer-specified reactions, Hg2+ reduction and methylmercury degradation, can be induced in natural waters and may participate in the geochemical cycling of mercury.
authors.affiliation: Department of General Microbiology, University of Copenhagen, Denmark.
authors.forename: L D
authors.initials: LD
authors.lastname: Rasmussen
authors.forename: R R
authors.initials: RR
authors.lastname: Turner
authors.forename: T
authors.initials: T
authors.lastname: Barkay
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics*; D001681:Biological Assay / Q000379:methods*; D018533:Biomass; D004268:DNA-Binding Proteins / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism*; D008628:Mercury / Q000378:metabolism; D008767:Methylmercury Compounds / Q000378:metabolism; D012097:Repressor Proteins; D012680:Sensitivity and Specificity; D015534:Trans-Activators; D014871:Water Microbiology
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; C051124:MerR protein, Bacteria; D008767:Methylmercury Compounds; D012097:Repressor Proteins; D015534:Trans-Activators; C064778:LuxR autoinducer binding proteins; D008628:Mercury