Specific metabolism related to sulfonamide tolerance and uptake in wetland plants

Wetland plants are proven to perform well in water treatment. However, the phytoremediation capability of wetland plants for antibiotics, especially the uptake and metabolism involved in vivo, is poorly understood. In this study, we investigated the removal, uptake, and specific metabolism by Canna indica and Iris pseudacorus of five sulfonamides (SAs) using hydroponic experiments for seven days. The removal of SAs ranged from 15.2% to 98.4% in the planted groups, whereas that in the unplanted control group was much lower (12.6%–39.9%). The accumulation of SAs in plants was in a concentration-dependent manner via an active process and is not a major removal mechanism (constituted 0.31%–3.62% of the total removal load in plant system). The results also showed differences in the removal and accumulation by plant species of SAs. The acetyl conjugates (N-acetyl SA) were formed, which significantly enhanced the uptake of SAs (P < 0.001) except sulfapyridine. The concentrations of N-acetyl SA accounted for only 0.4%–23.8% of the total SAs distribution in plants, suggesting the involvement of other metabolism pathways. Methylation and oxidation metabolites were identified in plant tissues and no SA-induced growth stress occurred, revealing that antibiotic metabolism in vivo should be associated with the ability of wetland plants to accumulate antibiotic and tolerate antibiotic stress.