Evaluation of the toxicity of the surfactant sodium dodecylbenzene sulfonate (LAS) and petroleum derivatives in the marine environment using the bioluminescent dinoflagellate Pyrocystis fusiformis as a bioindicator

• Grant number: 24/17699-1
• Support Opportunities: Scholarships in Brazil - Master
• Start date: May 01, 2025
• End date: April 30, 2027
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Chemical Oceanography
• Principal Investigator: Elisabete de Santis Braga da Graça Saraiva
• Grantee: Gabriella Ferreira de Andrade
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The assessment of the toxicity of contaminants in the marine environment is a very important part of environmental pollution monitoring. In this scenario, the use of bioluminescence for rapid assessments through ecotoxicological tests has shown promise. The bioluminescence of the dinoflagellate Pyrocystis fusiformis is a tool that can be used as an excellent indicator of the deleterious effects of different contaminants on marine organisms. In this study, standardized ecotoxicological tests will be applied to P. fusiformis from the Aidar & Kutner Microorganism Bank (BMAK) of the Oceanographic Institute of the University of São Paulo. The culture medium used is Guillard F/2 and the culture will be maintained in a 12-hour photoperiod at a temperature of 20 °C. To carry out the experiment, we will initially use sodium dodecylbenzenesulfonate (LAS - (CH¿¿)¿¿C¿H¿SO¿Na), one of the most widely used surfactants worldwide. In addition to crude oil, some of its derivatives will be tested, starting with turpentine and including other derived substances. The experimental design must follow the standardized ecotoxicological test standards ABNT NBR 12648, considering that, after the exposure period, the bioluminescence and population growth of the dinoglagellate will be evaluated through cell density data and observations of morphological changes in membranes or other structures visible under the microscope. During the experiment, Erlenmeyer flasks with a final volume of 100 mL and an approximate concentration of 3000 cells mL¿¹ will be used. Different concentrations of the pollutants will be used in addition to the control and the exposure will last 24 hours. The Tecan Infinite® luminometer will be used to measure bioluminescence. Cell density will be measured in the Sedgewick-Rafter counting chamber and the cells will be counted in a Leica model DME® optical microscope. It is expected that as the concentration of the contaminant increases, there will be a reduction in light emission, caused by damage and death of the organisms, which will affect population density. The impacts on bioluminescence may be related to cellular damage, including the rupture of the membranes of scintillons, organelles that house the luciferin-luciferase enzyme complex. Lethality may be observed by low light emission and by the observation of dead cells in the Sedgewick-Rafter chamber and also by cells with anomalies, such as the encysted and extroverted nucleus and the damaged cell membrane associated with the entry of surfactant, oil and derivatives into the cell. Thus, the effects of surfactant and oil on the bioluminescence of the bioluminescent dinoflagellate P. fusiformis may be evaluated for use as a tool with innovative technological potential and rapid response in environmental impact assessment.