Cultivable bacteria contribute to the removal of diclofenac and naproxen mix in a constructed wetland with Typha latifolia.

Abstract

Constructed wetlands are used to remove diclofenac and naproxen from wastewater. However, the role of plants and their root-associated bacteria in removing these pharmaceuticals is still unknown. In this work, bacteria were isolated from the roots of Typha latifolia cultivated in a constructed wetland to treat a diclofenac and naproxen mix. 16S rDNA sequencing indicated that bacterial isolates belong to the Pseudomonas, Serratia, and Rahnella genera. All bacterial isolates showed tolerance to high concentrations of diclofenac and naproxen and had differential laccase activity, phosphate-solubilizing activity, and indole acetic acid production.Bacteria were grouped into three consortia A (0-30 cm), B (50-80 cm), and C (100-130 cm), according to the site from which they were isolated in the wetland. Plant-bacteria interaction assays were conducted to determine the removal capacity of diclofenac and naproxen mix by the bacterial consortia or their interaction with T. latifolia. The results showed that all bacterial consortia removed over 50% of diclofenac and naproxen, while in their interaction with T. latifolia the removal capacity increased to over 70%. Consortium B was the most efficient in removing diclofenac and naproxen, with removal rates of 63.85 ± 0.45% and 74.93 ± 0.75%, respectively. Meanwhile, in the interaction of consortium B with T. latifolia, the removal of diclofenac and naproxen increased to 82.27 ± 0.30% and 88.12 ± 1.23%, respectively. Overall, the results indicated that T. latifolia and its root-associated bacteria removed the diclofenac and naproxen mix in the constructed wetland, contributing to understanding the role of the plant and bacteria in removing emerging contaminants. Therefore, the interaction of T. latifolia and its root-associated bacteria could potentially be used in strategies to remove emerging contaminants from wastewater.