An assessment of the potential of the microbial assay for risk assessment (MARA) for ecotoxicological testing

Bi Fai, Patricia and Grant, Alastair ORCID: (2010) An assessment of the potential of the microbial assay for risk assessment (MARA) for ecotoxicological testing. Ecotoxicology, 19 (8). 1626–1633. ISSN 1573-3017

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Rapid microscale toxicity tests make it possible to screen large numbers of compounds and greatly simplify toxicity identification evaluation and other effect directed chemical analyses of effluents or environmental samples. Tests using Vibrio fischeri (such as Microtox®) detect toxicants that cause non-specific narcosis, but are insensitive to other important classes of contaminants. The microbial assay for risk assessment (MARA) is a 24 h multi-species test that seeks to address this problem by using a battery of ten bacteria and a fungus. But there has been little independent evaluation of this test, and there is no published information on its sensitivity to pesticides. Here, we assess the performance of MARA using a range of toxicants including reference chemicals, fungicides and environmental samples. Mean MARA microbial toxic concentrations and IC20s (20% Inhibitory concentrations) indicate the toxicant concentrations affecting the more sensitive micro-organisms, while the mean IC50 (50% Inhibitory concentration) was found to be the concentration that was toxic to most MARA species. For the two fungicides tested, the yeast (Pichia anomalia) was the most sensitive of the ten MARA species, and was more sensitive than the nine other yeasts tested. The test may be particularly valuable for work with fungicides. Mean MARA IC50s were comparable to values for nine other yeast species and the lowest individual IC50s for each toxicant were comparable to reported IC50s for Daphnia magna, Selenastrum capricornutum and Microtox® bioassays. MARA organisms exhibited more variable sensitivities, with the most sensitive organism being different for different samples, enhancing the likelihood of toxicity detection and giving a toxicity "fingerprint" that may help identify toxicants. The test, therefore, has great potential and would be valuable for ecotoxicological testing of pollutants.

Item Type: Article
Faculty \ School: Faculty of Science > School of Environmental Sciences
UEA Research Groups: Faculty of Science > Research Centres > Centre for Ecology, Evolution and Conservation
Faculty of Science > Research Groups > Environmental Biology
Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences
Faculty of Science > Research Groups > Resources, Sustainability and Governance (former - to 2018)
Faculty of Science > Research Groups > Marine and Atmospheric Sciences (former - to 2017)
Depositing User: Rosie Cullington
Date Deposited: 02 Feb 2011 15:52
Last Modified: 15 Dec 2022 01:28
DOI: 10.1007/s10646-010-0548-2

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