The phytoremediation capacity of Lemna minor prevents deleterious effects of anti-HIV drugs to nontarget organisms.

We investigated physiological responses of Lemna minor plants and their capacity to remove tenofovir (TNF; 412 ng l-1), lamivudine (LMV; 5428 ng l-1) and/or efavirenz (EFV; 4000 ng l-1) from water through phytoremediation. In addition, the toxicological safety of water contaminated with these drugs after treatment with L. minor plants to photosynthetic microorganisms (Synechococcus elongatus and Chlorococcum infusionum) was evaluated. The tested environmental representative concentrations of drugs did not have a toxic effect on L. minor, and their tolerance mechanisms involved an increase in the activity of P450 and antioxidant enzymes (catalase and ascorbate peroxidase). L. minor accumulated significant quantities of TNF, LMV and EFV from the media (>70%), and the interactive effect of LMV and EFV increased EFV uptake by plants submitted to binary or tertiary mixture of drugs. Photosynthetic microorganisms exposed to TNF + LMV + EFV showed toxicological symptoms which were not observed when exposed to contaminated water previously treated with L. minor. An increased H2O2 concentrations but no oxidative damage in S. elongatus cells exposed to non-contaminated water treated with L. minor was observed. Due to its capacity to tolerate and reclaim anti-HIV drugs, L. minor plants must be considered in phytoremediation programs. They constitute a natural-based solution to decrease environmental contamination by anti-HIV drugs and toxicological effects of these pharmaceuticals to nontarget organisms.

The Role of H2O2-Scavenging Enzymes (Ascorbate Peroxidase and Catalase) in the Tolerance of Lemna minor to Antibiotics: Implications for Phytoremediation.

We investigated the individual and combined contributions of two distinct heme proteins namely, ascorbate peroxidase (APX) and catalase (CAT) on the tolerance of Lemna minor plants to antibiotics. For our investigation, we used specific inhibitors of these two H2O2-scavenging enzymes (p-aminophenol, 3-amino,1,2,4-triazole, and salicylic acid). APX activity was central for the tolerance of this aquatic plant to amoxicillin (AMX), whereas CAT activity was important for avoiding oxidative damage when exposed to ciprofloxacin (CIP). Both monitored enzymes had important roles in the tolerance of Lemna minor to erythromycin (ERY). The use of molecular kinetic approaches to detect and increase APX and/or CAT scavenging activities could enhance tolerance, and, therefore, improve the use of L. minor plants to reclaim antibiotics from water bodies.