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 μg/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 those 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.