Antagonistic Toxic Effects of Surfactants Mixtures to Bacteria Pseudomonas putida and Marine Microalgae Phaeodactylum tricornutum

Abstract

Surfactants can be found in an ever-widening variety of products and applications, in which the combination of several types of surfactants is used to reinforce their properties, looking for synergistic effects between them. After use, they tend to be discarded into wastewater, ending up in aquatic bodies with concerning harmful and toxic effects. The aim of this study is the toxicological assessment of three anionic surfactants (ether carboxylic derivative, EC) and three amphoteric surfactants (amine-oxide-based, AO), individually and in binary mixtures of them (1:1 w/w), to bacteria Pseudomonas putida and marine microalgae Phaeodactylum tricornutum. Critical Micelle Concentration (CMC) was determined to demonstrate the capacity to reduce surface tension and the toxicity of the surfactants and mixtures. Zeta potential (ζ-potential) and micelle diameter (MD) were also determined to confirm the formation of mixed surfactant micelles. The Model of Toxic Units (MTUs) was used to quantify the interactions of surfactants in binary mixtures and to predict if the concentration addition or response addition principle can be assumed for each mixture. The results showed a higher sensitivity of microalgae P. tricornutum to the surfactants tested and their mixtures than bacteria P. putida. Antagonism toxic effects have been detected in the mixture of EC + AO and in one binary mixture of different AOs; this is to say, the mixtures showed lower toxicity than expected.

Synthesis and Characterization of Environmentally Friendly Chitosan–Arabic Gum Nanoparticles for Encapsulation of Oregano Essential Oil in Pickering Emulsion

“…A Zetasizer Ultra (Malver Panalytical Ltd., Malvern, UK) was used to measure the size and zeta potential. The size was measured using a dynamic light scattering (DLS) technique, while the zeta potential was measured by electrophoretic light scattering (ELS) [28]. The instrument's settings were optimized automatically by means of ZS XPLORER software v. 3.2.1.11 (Malvern Panalytical Ltd., Malvern, UK).…”

Toxicity Mechanisms of Mixtures of Anionic and Non-Ionic Surfactants

“…In the case of surfactants, while individual studies of them can provide valuable information, they may not reflect real-world exposure to multiple surfactants at once. Synergistic or antagonistic effects stem from the combined toxicity of surfactants, meaning that combined effects are greater or lower than the sum of the individual effects [1,2].…”

Colloidal and Thermal Stability of Three‐Component Hybrid Materials Containing Clay Mineral, Polysaccharide and Surfactant

“…Therefore, to explain the mechanism of synergistic effects, it is necessary to take into account, among others, intermolecular interactions. [43,44] Cationic cellulose (CC), alginic acid (AA), hydroxyethyl cellulose (HEC) with the addition of Tritons were adsorbed on halloysite (NÀ H). Tritons X-are chemically inert detergents.…”

“…Usually the synergistic effect is observed after addition of surfactants, which is a consequence of interactions between the components of systems both in the bulk and on the surface (inside the mixed adsorption layer). Therefore, to explain the mechanism of synergistic effects, it is necessary to take into account, among others, intermolecular interactions [43,44] …”