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Rapid and cost-effective multiparameter toxicity tests for soil microorganisms.
G Carbonell1, M V Pablos, P García
1Department of Environmentally Sustainable Development, INIA, Madrid, Spain. carbonel@inia.es
The Science of the Total Environment
|May 10, 2000
Summary
Biochemical markers like beta-galactosidase and dehydrogenase show promise for cost-effective soil microorganism toxicity tests, unlike DNA quantification methods. These enzymatic activities effectively measured chemical impacts in various soil exposure scenarios.
Area of Science:
- Environmental toxicology
- Soil microbiology
- Biochemical assays
Background:
- Assessing soil microorganism toxicity is crucial for environmental health.
- Traditional toxicity tests can be time-consuming and expensive.
- Developing cost-effective and rapid bioassays is essential for routine environmental monitoring.
Purpose of the Study:
- To evaluate biochemical parameters, including DNA quantification and enzymatic activities (beta-galactosidase, dehydrogenase), as potential endpoints for cost-effective soil toxicity tests.
- To assess the suitability of these parameters in different testing systems: 24-h dose-response assays, soil column leaching studies, and multispecies miniaturised terrestrial systems (MTS).
- To investigate the effects of four different chemicals (copper, a new herbicide, thiabendazole, and fenthion) on soil microbial activity.
Main Methods:
- Developed a classical 24-h dose-response assay.
- Incorporated soil column leaching studies and multispecies miniaturised terrestrial systems (MTS).
- Quantified DNA and measured beta-galactosidase and dehydrogenase activities following exposure to test chemicals.
Main Results:
- Rapid DNA quantification was inadequate due to humic acid interference and was time-consuming and expensive.
- Beta-galactosidase and dehydrogenase activities proved effective toxicity endpoints.
- Copper, herbicide, thiabendazole, and fenthion exhibited varying degrees of inhibition on enzymatic activities, with results dependent on chemical properties and application methods (e.g., thiabendazole's low mobility).
- Enzymatic activities successfully measured microbial responses in soil columns and MTS.
Conclusions:
- Enzymatic activities (beta-galactosidase and dehydrogenase) are suitable and cost-effective endpoints for soil toxicity bioassays.
- DNA quantification is not recommended for rapid, cost-effective soil toxicity testing due to technical limitations.
- The study demonstrates the utility of biochemical parameters in assessing the ecotoxicological impact of chemicals in soil ecosystems.