MARA

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MARA

• A Microbial Array for Ecotoxicity Testing

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Contents

• This presentation covers 3 areas
• The drivers behind ecotoxicity testing
• Perspective of tests
• Conventional
• Micro-scale tests
• MARA
• Features
• Protocol
• Capabilities

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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

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Legislation

• Terrestrial environment
• Ecological Risk Assessment (ERA)
• Contaminated Land Regulations
• Landfill
• Landfill (Directive) Regulations.

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Ecotoxicity Testing

• Requires a measure of direct toxicity, taking
  into account
• Whole sample toxicity
• Interactive effects
• Unknown chemicals

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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

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Important Criteria for Micro-Scale Ecotoxicity
Tests

• simplicity
• speed
• reproducibility
• precision
• sensitivity

• Accuracy
• standardisation
• cost effectiveness
• convenience
• information

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Microbial Array

• Benefits of using micro-organisms
• Rapid growth
• Small size
• Large number tested
• No ethical issues
• Diversity

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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

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MARA Species

• The MARA test includes genetically diverse
  organisms from the following groups

• Prokaryotes
• Gram ve
• Gram ve
• a-proteobacteria
• ß-proteobacteria
• ?-proteobacteria
• Eukaryote
• yeast

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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

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Protocol
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Protocol
Serial Dilution
Reconstitute
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Microbial Fingerprint (effluent)
A microbial fingerprint can be derived from the
analysis
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MARA Software Image Screen
The plate image is copied into the image analysis
software
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MARA Software Data Screen
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Species Response
When the data generated by the software is
plotted, each of the species shows a different
response to the toxicant.
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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

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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

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Tests Comparison

• MARA has also been compared with the following
  established tests
• Fish
• Algal
• Invertebrate
• Microtox?
• Respiration inhibition
• Nitrification inhibition

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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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Mara Starter Pack
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MARA Reagent Plate Packs

• MARA Plates
• 5, 10 or 20 pack sizes
• Reagent Kits
• Reagents 1, 2, 3 4
• 5 or 20 Plate formats

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Contact Details

• NCIMB Ltd, Ferguson Building, Craibstone Estate,
  Bucksburn, Aberdeen, AB21 9YA
• Tel [phone], Fax [phone]
  12 99,
• Email mara_at_ncimb.com
• Sales contact Carol Phillips, Technical contact
  Terry Dando