Effects of long-term exposure to oxytetracycline on phytoremediation of swine wastewater via duckweed systems.

The effects of antibiotics on phytoremediation systems have attracted widespread attention to high concentrations of antibiotics in livestock wastewater. In this work, the effects of oxytetracycline (OTC) whose concentration was 0.05-1.00 mg/L on swine wastewater treatment by a duckweed-based phytoremediation systems were explored, including oxidative stress, nutrient production, bioconcentration, and community-level physiological profile. Results showed that the levels of H2O2 and peroxidases (PODs) of duckweed increased with an increase of OTC in the first 8 days. However, oxidative stress of duckweed disappeared after 18 days of exposure, except for 0.05 and 1.00 mg/L. Although OTC has negative effects on the production of high-value nutrients in duckweed, 0.05 and 0.25 mg/L OTC promoted the synthesis of starches and flavonoids, and the synthesis of vitamin C could restore after 28 days of exposure. In addition, a community-level physiological profile revealed that 0.05 mg/L OTC could significantly enhance the duckweed associated microorganisms metabolic activity. Therefore, this investigation adds to the understanding of antibiotics stress on high-value nutrients production in hydrophyte when was used to livestock wastewater management and also helps to clarify the metabolism profile of the phyllosphere and rhizosphere microbes; thereby providing new insight into effects of antibiotic on livestock wastewater phytoremediation.