Bacterial detection of the toxicity of dioxins, polychlorinated diphenyls, and polybrominated diphenyl ethers.

Polychlorinated dibenzo-p-dioxins (PCDDs), biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs) were found to induce several specific stresses within bacterial cells. Four different recombinant Escherichia coli with specific stress promoters (i.e., the recA responsive to DNA damage, fabA responsive to membrane damage, katG responsive to oxidative damage, and grpE responsive to protein damage) that were fused to the lux operon from Vibrio fischeri showed very unique specificities in terms of their stress responses in the presence of PCDD and PCBs. In addition, a recombinant bacterium with the lac promoter fused to the lux operon from Xenorhabdus luminescence also showed dose-dependent responses via a loss of bioluminescence because of the addition of the PCDDs and PCBs. Brominated diphenyl ethers (BDE) -47, -99, and -153 congeners, however, were not found to induce any stress within the bacterial cells, indicating that these chemicals do not stimulate any cellular stresses related to those tested. These three congeners, however, did result in different levels of general cellular toxicity, which was found to be dependent on the position of the bromine. Finally, the cellular toxicity within the bacteria was found to increase when exposed to mixtures of dioxins, PCBs, and PBDEs, possibly from synergistic effects.