Peroxidation levels in Eschericia coli as a potential toxicity marker: effect of nickel and methyl-parathion

The effects of nickel and methyl-parathion were studied in subinhibiting concentrations (40 and 62.5 micrograms/mL, respectively) on the levels of cellular peroxidation in Escherichia coli. These effects were evaluated using the thiobarbituric acid (TBA) test and the determination of lipofuscin-like substances. Both toxicants caused an increase in cellular peroxidation levels, although at the concentrations used, nickel was shown to be a better inducer than methyl-parathion. The TBA test gave more significant differences than the determination of lipofuscin-like substances when the control cultures were compared to these containing the toxicant. This finding reveals that the TBA test could be used as a toxicity marker in E. coli for the development of ecotoxicity biotests