Testing of polluted soil samples for genotoxic potential using Chlamydomonas reinhardtii
Dimitrova, Maria; Dimova, Evgeniya; Mitrovska, Zhana; Kapchina-Toteva, Veneta; Chankova, Stephka
Environmentally polluted soil samples were tested to evaluate their genotoxic potential. The samples were collected in the summer and autumn of 2004 from two plots (Lokorsko village and Yana village) situated nearby Sofia, Bulgaria. A bio-test based on the unicellular green alga Chlamydomonas reinhardtii (WT 137C) was used. The following endpoints were performed: colony forming ability ("clonal" assay) - for toxicity and genotoxicity (lethal mutations) assessment, induced "visible" mutants - for mutagenicity assessment, and biomarkers for oxidative stress (malondialdehyde, H2O2 and pigments). Our results revealed a strong toxic and genotoxic effect after treatment with all the four soil samples. The survival fraction (SF) was respectively 0.001, 0.15, 0.30 and 0.004 after treatment with the summer Lokorkso and Yana samples, and with the autumn Lokorsko and Yana samples. Strongest mutagenic effect was revealed after the treatment with the autumn Yana soil sample - the mutagenic index (MI) was 30. Both the summer and autumn samples caused changes in the biochemical markers - malondialdehyde, hydrogen peroxide and pigments, which is indicative of oxidative stress in the algal cells. The Regional Inspectorate of Environment and Water, Bulgaria (RIEW), reported that the level of heavy metal and pesticide pollution in the four soil samples was below and/or slightly above the maximum acceptable concentrations (MAC). Our results for both the toxic and genotoxic potential of the samples correlated well with the RIEW data. The endpoints chosen by us could be considered as ecologically relevant to reveal the harmful potential of the heavy metals available in the soil in concentrations below and/or slightly above MAC and traces of pesticides. Since unicellular green algae are a robust model for plants, the results obtained for Chlamydomonas reinhardtii could be extrapolated to higher plants.