Wastewater based epidemiology in countries with poor wastewater treatment - SARS-CoV-2 RNA in surface waters

Abstract

BACKGROUND Prokaryotic assays are of great interest in eco/geno-toxicology as they are short-term, simple and cost effective. Application of strains of Salmonella typhimurium with modifications such as increased cell wall permeability and lack of excision repair system is common for the detection of genotoxicity. Various eukaryotic models have been developed lately, such as fish derived cell lines, which can mimic the response of the aquatic organisms. Considering different level of cell organization among these models, difference in sensitivity is expected, yet only few studies address this topic. OBJECTIVES The major objective was to investigate genotoxic potential of extracts of surface water of the Danube and to compare the results obtained in applied prokaryotic and eukaryotic models. METHODS Surface water samples from 24 sites along the Danube River were extracted by LVSPE Horizon sampler providing relative enrichment factor (REF) of the extracts of 25,000x. For representative prokaryotic model the SOS/umuC assay with S. typhimurium TA1535/pSK1002 was used. Eukaryotic model comprised assessment of cytotoxicity by MTS test and assessment of genotoxicity by comet assay in ZFL (ZebraFish Liver) cells. RESULTS While none of the tested samples has induced SOS response, the result of MTS assay indicated that 11 of 24 samples were cytotoxic. In comet assay, genotoxic potential was found in 9 of 24 samples. Results indicated higher sensitivity of used eukaryotic model in comparison with prokaryotic. Applied prokaryotic assay is often suggested to be used as prescreening tool in diagnostics of genotoxic potential which by our opinion could be misleading.