Microbiome and Resistome Profiles along a Sewage-Effluent-Reservoir Trajectory Underline the Role of Natural Attenuation in Wastewater Stabilization Reservoirs

Research output: Contribution to journalResearch articleContributedpeer-review

Contributors

  • Inês Leão - , Catholic University of Portugal (Author)
  • Leron Khalifa - , Institute of Soil (Author)
  • Nicolas Gallois - , Université de Lorraine (Author)
  • Ivone Vaz-Moreira - , Catholic University of Portugal (Author)
  • Uli Klümper - , Chair of Limnology, Institute of Hydrobiology (Author)
  • Daniel Youdkes - , Institute of Soil (Author)
  • Shaked Palmony - , Fluence Corporation (Author)
  • Lotan Dagai - , Fluence Corporation (Author)
  • Thomas U Berendonk - , Institute of Hydrobiology, Chair of Limnology (Author)
  • Christophe Merlin - , Université de Lorraine (Author)
  • Célia M Manaia - , Catholic University of Portugal (Author)
  • Eddie Cytryn - , Institute of Soil (Author)

Abstract

Antibiotic-resistant bacteria and antibiotic resistance gene (ARGs) loads dissipate through sewage treatment plants to receiving aquatic environments, but the mechanisms that mitigate the spread of these ARGs are not well understood due to the complexity of full-scale systems and the difficulty of source tracking in downstream environments. To overcome this problem, we targeted a controlled experimental system comprising a semicommercial membrane-aerated bioreactor (MABR), whose effluents fed a 4,500-L polypropylene basin that mimicked effluent stabilization reservoirs and receiving aquatic ecosystems. We analyzed a large set of physicochemical measurements, concomitant with the cultivation of total and cefotaxime-resistant Escherichia coli, microbial community analyses, and quantitative PCR (qPCR)/digital droplet PCR (ddPCR) quantification of selected ARGs and mobile genetic elements (MGEs). The MABR removed most of the sewage-derived organic carbon and nitrogen, and simultaneously, E. coli, ARG, and MGE levels dropped by approximately 1.5- and 1.0-log unit mL-1, respectively. Similar levels of E. coli, ARGs, and MGEs were removed in the reservoir, but interestingly, unlike in the MABR, the relative abundance (normalized to 16S rRNA gene-inferred total bacterial abundance) of these genes also decreased. Microbial community analyses revealed the substantial shifts in bacterial and eukaryotic community composition in the reservoir relative to the MABR. Collectively, our observations lead us to conclude that the removal of ARGs in the MABR is mainly a consequence of treatment-facilitated biomass removal, whereas in the stabilization reservoir, mitigation is linked to natural attenuation associated with ecosystem functioning, which includes abiotic parameters, and the development of native microbiomes that prevent the establishment of wastewater-derived bacteria and associated ARGs. IMPORTANCE Wastewater treatment plants are sources of antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs), which can contaminate receiving aquatic environments and contribute to antibiotic resistance. We focused on a controlled experimental system comprising a semicommercial membrane-aerated bioreactor (MABR) that treated raw sewage, whose effluents fed a 4,500-L polypropylene basin that mimicked effluent stabilization reservoirs. We evaluated ARB and ARG dynamics across the raw-sewage-MABR-effluent trajectory, concomitant with evaluation of microbial community composition and physicochemical parameters, in an attempt to identify mechanisms associated with ARB and ARG dissipation. We found that removal of ARB and ARGs in the MABR was primarily associated with bacterial death or sludge removal, whereas in the reservoir it was attributed to the inability of ARBs and associated ARGs to colonize the reservoir due to a dynamic and persistent microbial community. The study demonstrates the importance of ecosystem functioning in removing microbial contaminants from wastewater.

Details

Original languageEnglish
Pages (from-to)e0017023
Number of pages16
JournalApplied and environmental microbiology
Volume89
Issue number6
Early online date18 May 2023
Publication statusPublished - 18 May 2023
Peer-reviewedYes

External IDs

unpaywall 10.1128/aem.00170-23
WOS 000990237200001
Scopus 85164069237
ORCID /0000-0002-4169-6548/work/142247385

Keywords

Keywords

  • Antibiotic resistance genes, Antibiotic-resistant bacteria, Community shifts, ddPCR, Ecological barriers, Microbiome, Mobile genetic elements, qPCR, Wastewater treatment, Genes, Bacterial, Sewage/microbiology, Angiotensin Receptor Antagonists, Bacteria/genetics, Polypropylenes, RNA, Ribosomal, 16S/genetics, Escherichia coli/genetics, Wastewater, Anti-Bacterial Agents/pharmacology, Microbiota, Angiotensin-Converting Enzyme Inhibitors, wastewater treatment, antibiotic resistance genes, ecological barriers, mobile genetic elements, microbiome, antibiotic-resistant bacteria, community shifts

Library keywords