Use of bacterial tests (the VITOTOX® genotoxicity test and the BIOMET heavy metal test) to analyze chemicals and environmental samples

Abstract

Several bacterial biotests for the detection of toxicity, genotoxicity or bioavailable heavy metals were developed at VITO and further improved for environmental testing. The VITOTOX@ test, which was originally developed for the detection of genotoxicity and toxicity of pure chemicals, was further improved for testing of environmental sampies. In the improved VITOTOX test, 2 bacterial strains are used, one to determine genotoxicity and a second strain as control for toxicity and factors influencing the activity of the lux reporter system. The "genotoxicity tester" strain is Salmonella typhimurium TA104 (pMOLl068). On pMOLl068, the Vibrio fischeri luxCDABE operon was placed under the control of an Escherichia coli RecN promoter derivative mutated in the second LexA binding site. A control strain, named S. typhimurium TA104 pr1 that contains the luxCDABE-genes under control of an Alcaligenes eutrophus constitutive promoter, was included in the VITOTOX@ test to avoid "false positive" results with substances able to enhance bacterial bioluminescence. With the improved VITOTOX test, a very good correlation was found with the Ames test. In addition, the VITOTOX test tumed out to be more accurate and sensitive than the SOS Chromotest. The VITOTOX test was further used to evaluate the bioremediation of PAH contarninated soils. The results obtained showed that during the bioremediation degradation interrnediates were forrned that had strong genotoxic potential. This result demonstrates the importance of ecotoxicological testing as a complementary approach for the evaluation of successful bioremediation of P AH contaminated soils. The BIOMET assay was developed in order to quantify the bioavailable metal fraction in environmental sampIes and was successfully tested on various environmental sampies such as soils, sludges, river sediments, fly ashes and slags. The BIOMET bacterial test appeared to be a simple, rapid and relevant assay to quantify the bioavailable metal fraction in soils, sludges or other environmental sampies.