Ecotoxicological test (microtox)

The Microtox ecotoxicological test is a rapid and sensitive method used to assess the acute toxicity of a sample to marine microorganisms . It is based on the measurement of bioluminescence produced by the bacterium Aliivibrio fischeri (formerly Vibrio fischeri), whose light intensity decreases proportionally to the toxicity of the tested medium.

This method allows the determination of the inhibitory concentration (IC50) , corresponding to the sample concentration causing 50% inhibition of bacterial luminescence after a defined exposure period.

The Microtox test is a powerful screening tool for:

• Detect the overall toxicity of a sample (complex mixture of compounds).
• Identify sublethal effects on aquatic microorganisms.
• Assess the environmental safety of products before they are placed on the market.

Analytical method

The Microtox test is standardized (ISO 11348, ASTM D5660) and follows the following steps:

1. Preparation of freeze-dried bacterial suspensions.
2. Contacting the sample (liquid or solubilized solid) with the Aliivibrio fischeri strain.
3. Measurement of luminescence before and after exposure (usually at 5, 15 or 30 minutes).
4. Calculation of the IC50 according to the dose-response curve.

This method is particularly useful for complex or non-specific , as it does not require prior knowledge of the chemical composition of the substance being tested.

Affected matrices

The Microtox test can be applied to a wide range of matrices:

• Wastewater, leachate, industrial or domestic effluents.
• Extracts from materials or packaging likely to release toxic compounds.
• Water-based chemicals and cosmetic formulations
• Biocides, detergents, lubricants, inks and solvents.
• Soils and sediments after aqueous extraction.

Industrial and regulatory applications

The Microtox ecotoxicological test is widely used in the fields of:

• From the environment , to assess the toxicity of liquid discharges or leachates of materials.
• Packaging and polymers , in order to check the absence of toxic substances likely to migrate.
• Cosmetics and fine chemicals , to control the safety of formulations with respect to aquatic microorganisms.
• Biotechnologies and research , for the characterization of effluents, environmental monitoring or the development of eco-responsible alternatives.

This test is complementary to other ecotoxicological tests (algae, daphnia, fish) required in environmental impact studies or REACH and CLP regulatory assessments .

Related analyses

The Microtox test can be combined with several analyses for a complete environmental safety assessment:

• SVHC test, substances of very high concern for the detection of hazardous compounds.
• Measurement of a pollutant in a sample to quantify specific contaminants.
• Study of chemical corrosion to assess the degradation of materials in aggressive environments.
• Thermal degradation analysis to understand the behavior of polymers exposed to heat.

YesWeLab expertise

YesWeLab provides a network of ISO 17025 and COFRAC accredited laboratories , experts in environmental and ecotoxicological analyses .

Thanks to the YesWeLab digital platform , you can centralize your analysis requests , track your samples online and access your complete reports, thus simplifying the management of your environmental studies.