Biodegradation of metoprolol in oxic and anoxic hyporheic zone sediments: unexpected effects on microbial communities

Abstract

Metoprolol is widely used as a beta-blocker and considered an emerging contaminant of environmental concern due to pseudo persistence in wastewater effluents that poses a potential ecotoxicological threat to aquatic ecosystems. Microbial removal of metoprolol in the redox-delineated hyporheic zone (HZ) was investigated using streambed sediments supplemented with 15 or 150 μM metoprolol in a laboratory microcosm incubation under oxic and anoxic conditions. Metoprolol disappeared from the aqueous phase under oxic and anoxic conditions within 65 and 72 days, respectively. Metoprolol was refed twice after initial depletion resulting in accelerated disappearance under both conditions. Metoprolol disappearance was marginal in sterile control microcosms with autoclaved sediment. Metoprolol was transformed mainly to metoprolol acid in oxic microcosms, while metoprolol acid and α-hydroxymetoprolol were formed in anoxic microcosms. Transformation products were transient and disappeared within 30 days under both conditions. Effects of metoprolol on the HZ bacterial community were evaluated using DNA- and RNA-based time-resolved amplicon Illumina MiSeq sequencing targeting the 16S rRNA gene and 16S rRNA, respectively, and were prominent on 16S rRNA rather than 16S rRNA gene level suggesting moderate metoprolol-induced activity-level changes. A positive impact of metoprolol on Sphingomonadaceae and Enterobacteriaceae under oxic and anoxic conditions, respectively, was observed. Nitrifiers were impaired by metoprolol under oxic and anoxic conditions. Collectively, our findings revealed high metoprolol biodegradation potentials in the hyporheic zone under contrasting redox conditions associated with changes in the active microbial communities, thus contributing to the attenuation of micropollutants. Key points • High biotic oxic and anoxic metoprolol degradation potentials in the hyporheic zone. • Key metoprolol-associated taxa included Sphingomonadaceae, Enterobacteraceae, and Promicromonosporaceae. • Negative impact of metoprolol on nitrifiers.

Nanocomposite PVDF/TiO2 Photocatalytic Membranes for Micropollutant Removal in Secondary Effluent

“…In addition, the long-term effects of its metabolites have not been systematically studied [6]. Likewise, MTP (see Figure 1b) is a persistent MP with potential ecotoxicological threat to aquatic ecosystems [8]. Photocatalysis has emerged recently as a promising green technology to remove MPs from water.…”

Metoprolol elicits neurobehavioral insufficiency and oxidative damage in nontarget Nauphoeta cinerea nymphs

“…Metoprolol is ranked among the top 20 frequently prescribed drugs in the United States and its consumption has been snowballing yearly across the globe 4,5 . Owing to the extensive use in human and veterinary medicine, metoprolol is frequently been detected in various environmental matrices globally, thus constituting a contaminant of emerging concern 6–8 . The aquatic environment is largely contaminated with metoprolol through discharge of sewage treatment plants effluents while the terrestrial environment is often contaminated through sewage sludge disposal, irrigation of crops with wastewater, feces discharged by animals, dumping of expired drugs into landfills as well as the direct application of animal manure for soil amendment 9–11 .…”

“…Metoprolol at 10 ng/L, 10 μg/L, and 10 mg/L induced oxidative damage in fish Cyprinus carpio at 12, 24, 48, 72, and 96 h posttreatment 20 . The noxious impact of metoprolol on these organisms suggests a public health threat and an emerging scientific interest 6,7 . Unfortunately, environmental risks of pharmaceuticals to nontarget organisms are not included in the monitoring framework possibly due to inadequate bioassays to assess their biological effects.…”

“…4,5 Owing to the extensive use in human and veterinary medicine, metoprolol is frequently been detected in various environmental matrices globally, thus constituting a contaminant of emerging concern. [6][7][8] The aquatic environment is largely contaminated with metoprolol through discharge of sewage treatment plants effluents while the terrestrial environment is often contaminated through sewage sludge disposal, irrigation of crops with wastewater, feces discharged by animals, dumping of expired drugs into landfills as well as the direct application of animal manure for soil amendment. [9][10][11] Although arable soil is amended by organic urban and animal wastes, pharmaceuticals, and other micropollutants in these wastes are well acknowledged to cause unpremeditated negative consequences in the environment.…”

“…20 The noxious impact of metoprolol on these organisms suggests a public health threat and an emerging scientific interest. 6,7 Unfortunately, environmental risks of pharmaceuticals to nontarget organisms are not included in the monitoring framework possibly due to inadequate bioassays to assess their biological effects. Specifically, there is scantiness of research on the impact of metoprolol on insects, which play significant roles in the ecosystems.…”