Antibiotic Toxicity Isolated and as Binary Mixture to Freshwater Algae Raphidocelis subcapitata: Growth Inhibition, Prediction Model, and Environmental Risk Assessment

Abstract

Antibiotics in aqueous environments can have extremely adverse effects on non-targeted organisms. However, many research projects have only focused on the toxicological evaluation of individual antibiotics in various environments. In the present work, individual and binary mixture toxicity experiments have been conducted with the model organism Raphidocelis subcapitata (R. subcapitata), and a mixture concentration-response curve was established and contrasted with the estimated effects on the basis of both the concentration addition (CA) and the independent action (IA) models. In addition, different risk assessment methods were used and compared to evaluate the environmental risk of binary mixtures. The toxic ranking of the selected antibiotics to R. subcapitata was erythromycin (ERY) > sulfamethoxazole (SMX) > sulfamethazine (SMZ). In general, the conclusion of this study is that the adverse effects of binary mixtures are higher than the individual antibiotics. The CA model and RQSTU are more suitable for toxicity prediction and risk assessment of binary mixtures. This study reveals the potential ecological risks that antibiotics and their mixtures may pose to water ecosystems, thus providing scientific information for environmental quality regulation.

Features of the microalga Raphidocelis subcapitata: physiology and applications

“…Considering that in nature toxics are not present single but in a complex matrix of chemical species that can interact with each other leading to synergistic, antagonistic, or and unpredictable effects, R. subcapitata has been used in the evaluation of mixtures (mainly binary) of toxics (Chèvre and Gregorio 2013 ). These studies started with the evaluation of pesticides (Mansano et al 2017 ; Moreira et al 2020 ) and have been extended to other classes of toxics, such as metals (Reis et al 2021 ; Gebara et al 2023 ), antibiotics (Chang et al 2022 ), cytostatic drugs (Venâncio et al 2023 ), biocides (Yang et al 2008 ), and PAHs (Kreutzer et al 2022 ).…”