Evaluation of the toxicity of several heavy metals by a fluorescent bacterial bioassay

✍ Scribed by Alberto Mariscal; Antonio García; Manuel Carnero; Jorge Gómez; Alfonso Pinedo; Joaquín Fernández-Crehuet

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 535 KB
• Volume: 15
• Category: Article
• ISSN: 0260-437X
• DOI: 10.1002/jat.2550150208

✦ Synopsis

This new bioassay determined the toxicity of chemical compounds dissolved in water by measuring the degree of inhibition of the ultraviolet light-stimulated fluorescence of Escherichia coli in a culture medium in which 4-methylumbelIifery1 P-D-glucuronide was the only carbon source. Inhibition produced by one of five heavymetal salts (Cd2+, Cr6+, Hg2+, Pb2+ or Zn2+) was the end-point and comparison standard to determine the ECso and minimum effective concentration (MEC) that produced a decrease of E. coli growth rate, increased doubling time and percentage inhibition and reduced numbers of generations; all these values were derived from the fluorescence signals. Only Cr6+ and Hgz+ at two concentrations (0.25 and 0.5 mg I-') almost completely inhibited this E. coli strain. All toxicant concentrations tested produced at least partial inhibitions of growth; Cr6', Hg2+ and Cd2+, in that order, were most toxic, and Pb2+ the least. Znz+ gave higher EC50 values at 3 h of incubation than at 4 h. The method was simple, rapid and inexpensive and would permit a large number of samples to be tested quickly.