Biological and synthetic surfactant exposure increases antimicrobial gene occurrence in a freshwater mixed microbial biofilm environment

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Aquatic habitats are particularly susceptible to chemical pollution, such as antimicrobials, from domestic, agricultural, and industrial sources. This has led to the rapid increase of antimicrobial resistance (AMR) gene prevalence. Alternate approaches to counteract pathogenic bacteria are in development including synthetic and biological surfactants such as sodium dodecyl sulfate (SDS) and rhamnolipids. In the aquatic environment, these surfactants may be present as pollutants with the potential to affect biofilm formation and AMR gene occurrence. We tested the effects of rhamnolipid and SDS on aquatic biofilms in a freshwater stream in Northern Ireland. We grew biofilms on contaminant exposure substrates deployed within the stream over 4 weeks. We then extracted DNA and carried out shotgun sequencing using a MinION portable sequencer to determine microbial community composition, with 16S rRNA analyses (64,678 classifiable reads identified), and AMR gene occurrence (81 instances of AMR genes over 9 AMR gene classes) through a metagenomic analysis. There were no significant changes in community composition within all systems; however, biofilm exposed to rhamnolipid had a greater number of unique taxa as compared to SDS treatments and controls. AMR gene prevalence was higher in surfactant‐treated biofilms, although not significant, with biofilm exposed to rhamnolipids having the highest presence of AMR genes and classes compared to the control or SDS treatments. Our results suggest that the presence of rhamnolipid encourages an increase in the prevalence of AMR genes in biofilms produced in mixed‐use water bodies.
Original languageEnglish
Article numbere1351
Pages (from-to)1-11
Number of pages12
Issue number2
Early online date17 Mar 2023
Publication statusPublished (in print/issue) - 30 Apr 2023

Bibliographical note

Funding Information:
The authors acknowledge the support of Ryan Lunenberg for assistance with microcosm placement. We also acknowledge Jeneil Biosurfactant, Saukville, WI, USA for providing rhamnolipid samples and the UK National River Flow Archive for the use of hydrological data for the Ballysally Blagh. Stephanie P. Gill is funded by an Ulster University Vice Chancellor's Doctoral Research Fellowship. William J. Snelling, James S. G. Dooley, and Nigel G. Ternan were supported by a Global Challenges Research Fund (GCRF) UK Research and Innovation (SAFEWATER; EPSRC Grant Reference EP/P032427/1). The study was partially funded by start‐up funding provided to WRH by the University of Ulster's School of Geography and Environmental Science.

Publisher Copyright:
© 2023 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.


  • 16S rRNA
  • AMR gene
  • aquatic
  • biofilm
  • rhamnolipid
  • surfactant
  • Anti-Infective Agents/pharmacology
  • RNA, Ribosomal, 16S/genetics
  • Biofilms
  • Fresh Water
  • Surface-Active Agents/pharmacology


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