NEW TOXICITY DETERMINATION METHOD THAT USES FLUORESCENT ASSAY OF ESCHERICHIA-COLI

We describe a new method that uses a fluorogenic bioassay of the beta- glucuronidase conversion of 4-methylumbelliferyl beta-D-glucuronide (M UG) to 4-methylumbelliferone to evaluate the individual toxic effects on Escherichia coli of Al3+, Cr6+, Hg2+ and Li+. This work was designe d to examine the effectiveness of this method to measure the effective ness ionic concentrations of either Al3+, Cr6+, Hg2+ or Li+, on the gr owth of E. coli in a minimal medium that had MUG as the only source of carbon. This method was simple and fast, and its toxicity detection s ensitivity was equal to, or greater than, existing bacterial bioassays . The use of the MUG substrate minimized the danger of interference br bacteria other than E. coli. Evaluations of toxicity in samples of pu blic drinking water proved equally sensitive.