Metabolomic insights into rhizosphere soil carbon component variations of Phragmites communis in the exposure of propranolol.

Propranolol (PRO) has been detected in water bodies worldwide, attributed to the incomplete removal by wastewater treatment processes. Although reports exist on the removal of PRO by wetland plants such as Phragmites communis, research on the impact of PRO on soil organic carbon (SOC) components in these plants' rhizospheres remains scarce. This investigation examined the impacts of 0.5 μg/L and 50 μg/L concentrations of PRO on the rhizosphere of P. communis over a 21-day laboratory experiment. PRO exposure slightly promoted root growth, notably enhancing fine root development at a lower concentration. A notable decrease in SOC content was observed in the PRO-treated samples: specifically, the proportion of mineral-associated organic carbon (MAOC) rose (from 47.90 % to 33.17 %), whereas the proportion of particulate organic carbon (POC) significantly declined following PRO treatment (from 52.10 % to 66.83 %). Moreover, Proteobacteria and Nitrospirae experienced significant promotion in the high-concentration samples while Bacteroidetes and Verrucomicrobia were inhibited. The metabolomic analysis demonstrated that glycine, serine, and threonine metabolism was the principal differential metabolic pathway in varying concentrations of PRO exposure. Additionally, across varying PRO concentrations, plant influence emerged as the predominant factor affecting POC alterations, whereas MAOC changes resulted from the synergistic interaction of plants and associated bacteria. The outcomes of this study mark a critical advancement towards a thorough assessment of PRO's impact on the rhizosphere of wetland plants, bearing significant ramifications for evaluating PRO's environmental effects.