Evaluating groundwater for its probable mutagenicity and genotoxicity using in vitro bioanalytical tools

The present study entails the investigation of mutagenic and genotoxic effect of groundwater samples collected from twenty four different locations of Malwa region (India) using in vitro bioassays, viz. Ames fluctuation test (with/without exogenous metabolic activation) using Salmonella typhimurium TA98 and TA100 strains, Vibrio harveyi bioluminescence assay using V. harveyi A16 strain (a dim luxE mutant), plasmid nicking assay, and comet assay. It was observed that the water samples of all the sites of study area demonstrated mutagenic activity on both strains of S. typhimurium. The different sampling periods caused variation in genotoxic intensity with summer samples showing higher mutagenicity values and, therefore, more genotoxic as compared to winter samples. However, V. harveyi bioluminescence assay was found to be comparatively less sensitive for genotoxicity screening of water samples. In plasmid nicking assay, 42% samples collected during summer were found to induce genotoxicity by increasing the level of DNA damage. To further establish the level of primary DNA damage, the alkaline version of comet assay was performed with human lymphocytes. No significant increase in DNA damage was seen as compared to negative control. Our results highlighted the significance of using more than one bioassay to evaluate the genotoxicity of water samples in different seasons. These results also demonstrate the need for further biological studies in this area for the detection of potentially genotoxic contaminants providing useful data in risk assessment.