| Abstract [eng] |
Vibrio fischeri bacteria are used as a bioobject of the standard bioluminescence quenching test (EN ISO 11348-3:1998), which is designed for the determination of the toxicity of single chemicals, their mixtures and environmental samples. The evaluation of the target sites of chemicals in redox enzyme systems (in vivo) and individual enzymes (in vitro) of V. fischeri bacteria is valuable tool for understanding the mechanisms of chemical action, for the prediction of mixture toxicity and explanation of the toxicodynamic effects. The use of multiple regression method revealed the different toxicodynamic effects of binary mixtures of Aroclor 1248 (A), oleic acid (OA) and elemental sulfur (S80) on bioluminescence of Vibrio fischeri and NADH:FMN oxidoreductase – luciferase in vitro. A and S80 acted additively with synergistic interaction in vivo and additively without significant interaction in vitro; A and OA acted antagonistically in both systems. OA and S80 caused an additive effect with antagonistic component of interaction in vivo and had additive effect with synergistic interaction in vitro. Toxicity of the individual pollutants (A, OA and S80) and their binary mixtures to bioluminescence diminished with increasing exposure time (30, 60 min) in the in vivo, but not in the in vitro system. It was indicated that A and OA, but not S80, enhanced ROS generation in V. fischeri cells. Contrary, S80 (greater than A and OA) enhanced reducing ability of cells. It is concluded that the principle target site of OA and S80 is the active center of the luciferase enzyme, and the main site of A action is a NADH:FMN oxidoreductase in the bioluminescence complex. |
