TOXICITY TESTING OF SYNTHETIC AND BIOGENIC SURFACTANTS ON MARINE MICROORGANISMS

The toxicity of four synthetic surfactants, two commercial oil dispersants, and six biosurfactants have been examinated. The test systems were (a) bacterial growth inhibition, (b) microalgae growth inhibition, (c) microflagellate growth inhibition, (d) biodegradation, and (e) bioluminescence inhibition (Microtox test). The multiplication of bacteria was stimulated by surfactants, while that of microflagellates and microalgae was inhibited. This may be due to the metabolic usage of surfactants, especially biosurfactants, by bacteria. The bioluminescence was very sensitive to surfactants. No toxicity could be detected with glucose-lipid, produced by the marine bacterium Alcaligenes sp. MM1. Most biosurfactants were degraded faster and possessed higher EC50 values then synthetic dispersants.