Synergistic Removal of Ciprofloxacin and Sulfamethoxazole by Lemna minor and Salvinia molesta in Mixed Culture: Implications for Phytoremediation of Antibiotic-Contaminated Water

Abstract

Aquatic macrophytes have been used for the removal of antibiotics from contaminated water. Here, we have studied the capacity of Lemna minor and Salvinia molesta to reclaim ciprofloxacin (1.5 µg Cipro L−1) and/or sulfamethoxazole (0.3 µg Sulfa L−1) from artificially contaminated waters when plants were exposed in monoculture (L. minor or S. molesta) or in mixed culture (L. minor + S. molesta). Neither Cipro nor Sulfa alone induced negative effects on plants. As shown by the Abbot modelling, Cipro and Sulfa displayed antagonistic effects on plants. In both species, increased H2O2 concentrations and antioxidant enzyme activities were observed in plants when grown together. Although the antibiotics showed natural degradation, their concentration in water from treatments with plants was significantly lower, indicating the ability of the plants to uptake the compounds. When in co-culture, greater growth rates were observed for both plant species, which resulted in greater Cipro and Sulfa removal in the mixed system when compared with those with plants in monoculture. Both plants showed tolerance to the studied concentrations of antibiotics, with greater antibiotic uptake being reported for S. molesta. Although at the tested concentrations the antibiotics did not induce negative effects on plants, exposure to Cipro changed the relative yield of S. molesta, which may result in effects on community structure. The use of both L. minor and S. molesta in artificial wetlands may increase the phytoremediation capacity of systems.