Purpose and Principle of the study – SESAMULS® WO
This study was performed in order to evaluate the toxicity of SESAMULS® WO (Polyglyceryl- 6 Pentaoleate, Sesame Oil, Malic Acid) in Desmodesmus subspicatus. This freshwater green alga was chosen as a typical species of phytoplankton.
The system response was the reduction of growth in a series of algal cultures (test units) exposed to various concentrations of a test item. The response was evaluated as a function of the exposure concentration in comparison with the average growth of replicate, unexposed control cultures. For full expression of the system response to toxic effects (optimal sensitivity), the cultures were allowed unrestricted exponential growth under nutrient sufficient conditions and continuous light for a sufficient period of time to measure reduction of the specific growth rate.
MATERIALS AND METHODS
Test Item
| Designation in Test Facility | 14121104N |
| Name | SESAMULS® WO |
| Batch No. | C0063 |
Storage
The test item was stored in a closed vessel dark and dry at room temperature.
Preparation
Due to the poor solubility of the test item, the water-accommodated fraction (WAF) of the concentrations to be tested was prepared. This was done by weighing the nominal loads (1 mg/L, 10 mg/L and 100 mg/L), adding the appropriate amount of nutrient medium (demineralised water enriched with minerals but without algae) and shaking for 24 hours. The resulting solutions were filtrated through 0.45 μm filters.
Positive Control
Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a separate reference test (GLP study).
Test System
Specification
Unicellular freshwater green alga.
| Genus |
Desmodesmus |
| Species |
subspicatus |
| SAG Strain Number |
86.81 |
| Taxonomic position |
Chlorophyta – Chlorophyceae |
Origin and Culture
The culture of Desmodesmus subspicatus was obtained in February 2014 by MBM Sciencebridge GmbH (Institut für Pflanzenphysiologie of Universität Göttingen). The algae are kept as stock culture on solid agar at 7 °C. From the stock culture, a permanent culture was prepared. From an aliquot of the permanent culture, the pre-culture was prepared.
Chemicals
All solutions were sterilised before use.
Composition of the Solutions:
| Stock solution I | |
| NH4Cl | 1500 mg |
| MgCl2*6H2O | 1200 mg |
| CaCl2*2H2O | 1800 mg |
| MgSO4*7H2O | 1500 mg |
| KH2PO4 | 180 mg |
| H2O deionized | ad 1000 mL |
| Stock solution II | |
| FeCl3*6H2O | 64 mg |
| Na2EDTA*2H2O | 100 mg |
| H2O deionized | ad 1000 mL |
| Stock solution III | |
| H3BO3 | 185 mg |
| MnCl2*4H2O | 415 mg |
| ZnCl2 | 3 mg |
| CoCl2*6H2O | 1.5 mg |
| CuCl2*2H2O | 0.01 mg |
| Na2MoO4*2H2O | 7 mg |
| H2O deionized | ad 1000 mL |
| Stock solution IV | |
| NaHCO3 | 50 mg |
| H2O deionized | ad 1000 mL |
| Pre-culture-medium | |
| Stock solution I | 10.0 mL |
| Stock solution II | 1.0 mL |
| Stock solution III | 1.0 mL |
| Stock solution IV | 1.0 mL |
| H2O deionized | ad 1000 mL |
| Nutrient-medium (10-fold concentrated) | |
| Stock solution I | 100 mL |
| Stock solution II | 10 mL |
| Stock solution III | 10 mL |
| Stock solution IV | 10 mL |
| H2O deionized | ad 1000 mL |
