Performance and bacterial community dynamics of hydroponically grown Iris pseudacorus L. during the treatment of antibiotic-enriched wastewater at low/normal temperature

Antibiotics are widely detected in the water environment, posing a serious threat to the health of humans and animals. The effect of levofloxacin (LOFL) on pollutant removal and the difference in the influence mechanisms at normal and low temperatures in constructed wetlands are worth discussing. A hydroponic culture experiment was designed with Iris pseudacorus L. at low and normal temperatures. LOFL (0?100 ?g/L) was added to the systems. The results indicated that the removal of pollutants was affected most by temperature, followed by LOFL concentration. At the same concentration of LOFL, the pollutant removal rate was significantly higher at normal temperature than at low temperature. Low concentrations of LOFL promoted the degradation of pollutants except TN under normal-temperature conditions. Compared with the results at low temperature, the bacterial community richness was higher and the diversity of bacterial communities was lower under normal-temperature conditions. The genera and the function of bacteria were greatly affected by antibiotic concentration, temperature and test time. A series of microorganisms resistant to antibiotics and low temperature were identified in this study. The results will provide valuable information and a reference for our understanding of the ecological effects of LOFL.

Automated summary

Antibiotics, particularly levofloxacin, in constructed wetlands have differential effects on pollutant removal at normal and low temperatures. Temperature and antibiotic concentration play significant roles in the removal of pollutants, with low concentrations of antibiotics promoting degradation of pollutants under normal temperature conditions. Bacterial community richness is higher and diversity lower at normal temperature, while bacterial genera and functions are greatly influenced by antibiotic concentration, temperature, and test time. This study identifies antibiotic and low temperature-resistant microorganisms, providing valuable information for understanding the ecological effects of levofloxacin.