title: Effects of three heavy metals on the bacteria growth kinetics: a bivariate model for toxicological assessment.
abstract: The effects of three heavy metals (Co, Ni and Cd) on the growth kinetics of five bacterial strains with different characteristics (Pseudomonas sp., Phaeobacter sp. strain 27-4, Listonella anguillarum, Carnobacterium piscicola and Leuconostoc mesenteroides subsp. lysis) were studied in a batch system. A bivariate model, function of time and dose, is proposed to describe simultaneously all the kinetic profiles obtained by incubating a microorganism at increasing concentrations of individual metals. This model combines the logistic equation for describing growth, with a modification of the cumulative Weibull's function for describing the dose-dependent variations of growth parameters. The comprehensive model thus obtained--which minimizes the effects of the experimental error--was statistically significant in all the studied cases, and it raises doubts about toxicological evaluations that are based on a single growth parameter, especially if it is not obtained from a kinetic equation. In lactic acid bacteria cultures (C. piscicola and L. mesenteroides), Cd induced remarkable differences in yield and time course of characteristic metabolites. A global parameter is defined (ED(50,τ): dose of toxic chemical that reduces the biomass of a culture by 50% compared to that produced by the control at the time corresponding to its semi maximum biomass) that allows comparing toxic effects on growth kinetics using a single value.
authors.affiliation: Grupo de Reciclado y Valorización de Materiales Residuales (REVAL), Instituto de Investigacións Mariñas (CSIC), r/Eduardo Cabello, 6, Vigo 36208, Galicia, Spain. diegorialconde@iim.csic.es
authors.forename: Diego
authors.initials: D
authors.lastname: Rial
authors.forename: José Antonio
authors.initials: JA
authors.lastname: Vázquez
authors.forename: Miguel Anxo
authors.initials: MA
authors.lastname: Murado
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000187:drug effects* / Q000254:growth & development* / Q000378:metabolism; D007700:Kinetics; D019216:Metals, Heavy / Q000378:metabolism / Q000633:toxicity*; D008962:Models, Theoretical
chemical_list: D019216:Metals, Heavy