Effect of metal mixtures on Salmonella enteritidis viability in synthetic sewage

We sought to determine the effect of 26 multiple metals solutions, containing Cd, Pb, As and/or Ni, on the viability of Salmonella enteritidis. We used the direct viable count effected by immunofluorescence technique (IFA-DVC) in comparison with the culturable cell count. The metals concentrations were prepared considering the single as well as the overall limits provided by Italian regulation on the water pollution. The mixtures containing nickel showed always toxicity more elevated than other metal solutions tested. Thus we consider too high the nickel law limit. The interactions among the elements, causing generally toxicity decrease, are very well assessable by IFA-DVC test. This method permits to calculate the lethal concentrations of toxicants on bacteria that play a pivotal role on the ecosystem components.