Detection and quantification of genotoxicity in wastewater‐treated Tetrahymena thermophila using the comet assay

Abstract

In the present study, the comet, or single-cell, gel electrophoresis assay was adapted for use with the ubiquitous unicellular protozoan Tetrahymena thermophila, and the method was evaluated for its ability to detect DNA damage induced by known genotoxins and wastewater samples. The original comet assay protocol was substantially modified (e.g., lower concentrations of detergents were used in the lysis buffer; electrophoresis time was reduced). Using the modified method, T. thermophila were subjected to short exposures of phenol, hydrogen peroxide, and formaldehyde, leading to concentration-dependent increases in DNA damage. The genotoxic potential of influent and effluent water samples from a local municipal wastewater treatment plant was evaluated. The results indicated that the influent wastewater was genotoxic and that the genotoxicity in the effluent water was substantially reduced. We assume employing T. thermophila in the use of the comet assay may become a cost-effective and reliable tool for genotoxicity screening and monitoring of wastewater and similar systems.

Ecotoxicological assessment of industrial effluent using duckweed (Lemna minor L.) as a test organism

“…Increasing concentrations of EMS produced significant dose-dependent increases in the median tail moment values. There are only few reports on use of Comet assay for the assessment of genotoxicity of surface and waste water in which mammalian, bacterial or protozoan cells/organisms are utilized (Lah et al 2004;Kungolos et al 2006;Ž egura et al 2009). Simplified Comet procedure modified for plants tissues allows rapid yet sensitive determination of DNA damage.…”

Perfluorooctanoic acid (PFOA) but not perfluorooctane sulfonate (PFOS) showed DNA damage in comet assay on Paramecium caudatum

“…Although euglena and tetrahymena were employed in comet assay (Aoyama et al, 2003;Lah et al, 2004), there has been no report about comet assay using paramecium. When live paramecia were embedded in agarose, the solidified agarose showed a track of paramecia which had swum in melted agar gel, making difficult to observe DNA damage with a fluorescent microscope.…”

Comet assay: a reliable tool for the assessment of DNA damage in different models

“…Its uniqueness lies in the fact that it has a somatic and a germ nucleus in the same cell. Therefore, it has been validated as a model organism for assessing DNA damage using a modified Comet assay protocol standardized with known mutagens such as phenol, hydrogen peroxide, and formaldehyde (Lah et al 2004). The method was then used for the assessment of genotoxic potential of influent and effluent water samples from a local municipal wastewater treatment plant (Lah et al 2004).…”

“…Therefore, it has been validated as a model organism for assessing DNA damage using a modified Comet assay protocol standardized with known mutagens such as phenol, hydrogen peroxide, and formaldehyde (Lah et al 2004). The method was then used for the assessment of genotoxic potential of influent and effluent water samples from a local municipal wastewater treatment plant (Lah et al 2004). The method provided an excellent, low-level detection of genotoxicants and proved to be a costeffective and reliable tool for genotoxicity screening of wastewater.…”