Experimental evolution of Pseudomonas putida under silver ion versus nanoparticle stress

Feng Dong, Ana C Quevedo, Xiang Wang, Eugenia Valsami-Jones, Jan-Ulrich Kreft

Research output: Contribution to journalArticlepeer-review


Whether the antibacterial properties of silver nanoparticles (AgNPs) are simply due to the release of silver ions (Ag+) or, additionally, nanoparticle-specific effects, is not clear. We used experimental evolution of the model environmental bacterium Pseudomonas putida to ask whether bacteria respond differently to Ag+ or AgNP treatment. We pre-evolved five cultures of strain KT2440 for 70 days without Ag to reduce confounding adaptations before dividing the fittest pre-evolved culture into five cultures each, evolving in the presence of low concentrations of Ag+, well-defined AgNPs or Ag-free controls for a further 75 days. The mutations in the Ag+ or AgNP evolved populations displayed different patterns that were statistically significant. The non-synonymous mutations in AgNP-treated populations were mostly associated with cell surface proteins, including cytoskeletal membrane protein (FtsZ), membrane sensor and regulator (EnvZ and GacS) and periplasmic protein (PP_2758). In contrast, Ag+ treatment was selected for mutations linked to cytoplasmic proteins, including metal ion transporter (TauB) and those with metal-binding domains (ThiL and PP_2397). These results suggest the existence of AgNP-specific effects, either caused by sustained delivery of Ag+ from AgNP dissolution, more proximate delivery from cell-surface bound AgNPs, or by direct AgNP action on the cell's outer membrane.

Original languageEnglish
Pages (from-to)905-918
Number of pages14
JournalEnvironmental Microbiology
Issue number2
Early online date13 Dec 2021
Publication statusPublished - Feb 2022

Bibliographical note

Funding Information:
We thank the Darwin Trust Edinburgh for Feng Dong's PhD scholarship and the Mexican National Council for Science and Technology (CONACyT) for Ana Carrazco Quevedo's PhD scholarship. We are indebted to Pablo Fuentes‐Utrilla and Emily Richardson from MicrobesNG ( http://www.microbesng.uk ) at the Institute for Microbiology and Infection (IMI) at the University of Birmingham (funded by the BBSRC, grant number BB/L024209/1) for sequencing and bioinformatic analysis. We are grateful for the support from the Natural Science Foundation of China (41907347) and the NERC via the Facility for Environmental Nanoscience Analysis and Characterisation (FENAC) at the University of Birmingham.

Publisher Copyright:
© 2021 Society for Applied Microbiology and John Wiley & Sons Ltd.


  • Ecology, Evolution, Behavior and Systematics
  • Microbiology

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Microbiology


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