Presentation on theme: "MARA A Microbial Array for Ecotoxicity Testing. Contents This presentation covers 3 areas: The drivers behind ecotoxicity testing Perspective of tests."— Presentation transcript:
Contents This presentation covers 3 areas: The drivers behind ecotoxicity testing Perspective of tests –Conventional –Micro-scale tests MARA –Features –Protocol –Capabilities
Legislation Aquatic environment –EC Directives Specific uses e.g. Freshwater Fish Directive Industry sectors e.g. TiO2 Directive Substances e.g. Dangerous substances Directive Products e.g. Detergents Directive Water Framework Directive (SWIFT – WFD) –Direct Toxicity Assessment / Integrated Pollution Prevention and Control
Ecotoxicity Testing Requires a measure of direct toxicity, taking into account: Whole sample toxicity Interactive effects Unknown chemicals
Micro-Scale Ecotoxicity Tests The acceptability of micro- scale ecotoxicity tests is well established, with a wide range available commercially. These include: Algae Invertebrates Higher Plants
Important Criteria for Micro-Scale Ecotoxicity Tests simplicity speed reproducibility precision sensitivity Accuracy standardisation cost effectiveness convenience information
Microbial Array Benefits of using micro-organisms –Rapid growth –Small size –Large number tested –No ethical issues –Diversity
What is MARA? MARA (Microbial Assay for Risk Assessment) The MARA product is a multi-species toxicity test based on an array of 11 micro-organisms that –is simple to use –provides a battery of tests within a test –produces data for 11 test results –can be used to produce toxic fingerprints of –chemicals or environmental samples –requires small sample volumes –is particularly suitable for use in environmental toxicity testing
MARA Species The MARA test includes genetically diverse organisms from the following groups: Prokaryotes Gram +ve Gram –ve –α-proteobacteria –β-proteobacteria –γ-proteobacteria Eukaryote yeast
Microbial Toxic Concentration Microbial Toxic Concentration (MTC) is a measurement developed for MARA which is used to express growth inhibition and is equivalent to an EC50 value. The benefits of this are: –Reduces complexity and simplifies interpretation –Knowledge of the shape of the growth curves is not required –Calculation uses area above and below total curve –Eliminates interpolation errors of classic EC50 determination –Sensitive, repeatable and reproducible
Species Response When the data generated by the software is plotted, each of the species shows a different response to the toxicant.
MARA Evaluation Summary Excellent repeatability Highly reproducible Sensitivity is comparable to other tests on the market Works well with organics Can indicate mode of action of chemicals Has been tested using confounding variables
Application of MARA MARA is capable of determining the toxicity of a wide range of environmental samples, including –Effluents –Waters Raw Final –Soils –Landfill leachates –Sewage sludges MARA also has significant application in the chemical and pharmaceutical industries, process monitoring and QC testing
Tests Comparison MARA has also been compared with the following established tests Fish Algal Invertebrate Microtox Respiration inhibition Nitrification inhibition
Benefits of MARA Multi-species Simple protocol Observations readily made Easy image storage Extensive testing feasibility Minimal space requirement Proprietary software – easy inference of results
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