Vibrio Fischeri Test Research Articles

Sensitivity limits and EC50 values of the Vibrio fischeri test for organic micropollutants in natural and spiked extracts from sediments

AbstractChemical analyses and bioassays were used in conjunction to assess the quality of sediments of the Venice lagoon. Organic micropollutants (polycyclic aromatic hydrocarbons [PAHs] polychlorinated biphenyls [PCBs], and chlorinated pesticides) were extracted from sediment samples and analyzed by gas chromatography after fractionation into classes of compounds. The Vibrio fischeri test was used to assess the acute toxicity of sediment extracts. The test was applied to organic extracts before cleanup and to extracts purified from sulfur and fractionated into single classes of compounds. Extracts before purification were much more toxic than single fractions. In particular, sulfur was toxic to V. fischeri. For PAHs and PCBs the 50% effective concentration (EC50) and EC20 values were determined using natural and spiked extracts (EC50 = 0.5 μg/ml and 1.4 μg/ml, respectively; EC20 = 0.13 μg/ml and 0.17 μg/ml). Sensitivity limits of the method for these compounds were also estimated as was an EC50 value of elemental sulfur dissolved in ethanol (0.022 μg/ml). A mathematical model was used to fit the concentration–response data to a sigmoid curve.

Use of semi-permeable membrane devices to monitor pollutants in water and assess their effects: A laboratory test and field verification

Uptake of eight pesticides of different classes (organochlorines, synthetic pyrethroids, dinitroanilines, amides) by semi-permeable membrane devices (SPMDs) was studied in a laboratory continuous-flow system. After 20 days of exposure, membrane concentration factors were in the range of 50 000–120 000 for all the analytes except for the amide herbicides propachlor and alachlor, which were not detected in any of the SPMDs. The kinetic data and mathematical models were used to calculate analyte uptake rate constants, SPMD lipid/water partition coefficients, average sampling rates and concentrations of the pesticides in water. To assess the effects of concentrated pesticides, standard bioassays ( Salmonella/histidine reversion assay and bioluminescence inhibition in Vibrio fischeri test) were incorporated in the SPMD technique. To test the method in an environmental situation, SPMDs were deployed in polluted sites in Lithuania. Polynuclear aromatic hydrocarbons were the major pollutants detected in the SPMDs deployed in the field. All the SPMD dialysates were highly toxic in the bioluminescence inhibition test but no mutagenic activity was observed in the Salmonella/histidine reversion assay.