, Volume 31, Issue 6, pp 1101–1114 | Cite as

Chromosomal Sil system contributes to silver resistance in E. coli ATCC 8739

  • Mariana Blanco MassaniEmail author
  • Jochen Klumpp
  • Madeleine Widmer
  • Christian Speck
  • Marc Nisple
  • Rainer Lehmann
  • Markus Schuppler


The rise of antibiotic resistance in pathogenic bacteria is endangering the efficacy of antibiotics, which consequently results in greater use of silver as a biocide. Chromosomal mapping of the Cus system or plasmid encoded Sil system and their relationship with silver resistance was studied for several gram-negative bacteria. However, only few reports investigated silver detoxification mediated by the Sil system integrated in Escherichia coli chromosome. Accordingly, this work aimed to study the Sil system in E. coli ATCC 8739 and to produce evidence for its role in silver resistance development. Silver resistance was induced in E. coli ATCC 8739 by stepwise passage in culture media containing increasing concentrations of AgNO3. The published genome of E. coli ATCC 8739 contains a region showing strong homology to the Sil system genes. The role of this region in E. coli ATCC 8739 was assessed by monitoring the expression of silC upon silver stress, which resulted in a 350-fold increased expression. De novo sequencing of the whole genome of a silver resistant strain derived from E. coli ATCC 8739 revealed mutations in ORFs putative for SilR and CusR. The silver resistant strain (E. coli AgNO3R) showed constitutive expression of silC which posed a cost of fitness resulting in retarded growth. Furthermore, E. coli AgNO3R exhibited cross-resistance to ciprofloxacin and a slightly increased tolerance to ampicillin. This study demonstrates that E. coli is able to develop resistance to silver, which may pose a threat towards an effective use of silver compounds as antiseptics.


Silver resistance Escherichia coli De novo sequencing Sil system silC expression qRT-PCR 



The authors are grateful for the support of MINCyT-ANPCyT, PICT Start-Up-2015-0027, PICT-2014-0585 and the National Institute of Industrial Technology (Argentina). The input given by Dr. Mario Hupfeld, Dr. Samuel Kilcher, and Dr. Matthew Dunne during the development of this work is also acknowledged.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Supplementary material

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Supplementary material 1 (PDF 15 kb)
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Supplementary material 2 (PDF 31 kb)
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Supplementary material 4 (PDF 159 kb)


  1. Copeland A, Lucas S, Lapidus A, Glavina Del Rio T, Dalin E, Tice H, Bruce D, Goodwin L, Pitluck S, Kiss H, Brettin T, Detter C, Han JC, Kuske CR, Schmutz J, Larimer F, Land M, Hauser L, Kyrpides N, Mikhailova N, Ingra P (2008) Escherichia coli ATCC 8739. A strain of E. coli lacking the major porin OmpC. Accessed 8 Sep 2017
  2. Crossman LC, Chaudhuri RR, Beatson SA, Wells TJ, Desvaux M, Cunningham AF, Petty NK, Mahon V, Brinkley C, Hobman JL, Savarino SJ, Turner SM, Pallen MJ, Penn CW, Parkhill J, Turner AK, Johnson TJ, Thomson NR, Smith SG, Henderson IR (2010) A commensal gone bad: complete genome sequence of the prototypical enterotoxigenic Escherichia coli strain H10407. J Bacteriol 192:5822–5831. CrossRefPubMedPubMedCentralGoogle Scholar
  3. Crozat E, Hindré T, Kühn L, Garin J, Lenski RE, Schneider D (2011) Altered regulation of the ompf porin by fis in Escherichia coli during an evolution experiment and between B and K-12 strains. J Bacteriol 193:429–440. CrossRefPubMedGoogle Scholar
  4. Çulha M, Kalay Ş, Sevim E, Pinarbaş M, Baş Y, Akpinar R, Karaoğlu ŞA (2017) Biocidal properties of maltose reduced silver nanoparticles against American foulbrood diseases pathogens. Biometals. CrossRefPubMedGoogle Scholar
  5. Delcour AH (2009) Outer membrane permeability and antibiotic resistance. Biochim Biophys Acta 1794:808–816. CrossRefPubMedGoogle Scholar
  6. Durán N, Durán M, de Jesus MB, Seabra AB, Fávaro WJ, Nakazato G (2016) Silver nanoparticles: a new view on mechanistic aspects on antimicrobial activity. Nanomed Nanotechnol Biol Med 12:789–799. CrossRefGoogle Scholar
  7. Egger S, Lehmann R, Height M, Loessner M, Schuppler M (2009) Antimicrobial properties of a novel silver–silica nanocomposite material. Appl Environ Microbiol 75:2973–2976. CrossRefPubMedPubMedCentralGoogle Scholar
  8. EUCAST (2000) EUCAST Definitive Document E.Def 1.2, May 2000: terminology relating to methods for the determination of susceptibility of bacteria to antimicrobial agents. Clin Microbiol Infect 6:503–508. CrossRefGoogle Scholar
  9. EUCAST (2003) EUCAST DISCUSSION DOCUMENT E.Dis 5.1 determination of minimum inhibitory concentrations (MICs) of antibacterial agents by broth dilution. Clin Microbiol Infect 9:1–7. CrossRefGoogle Scholar
  10. EUCAST (2017) MIC distributions and ECOFFs. Accessed 9 Sep 2017
  11. Fernández L, Hancock REW (2012) Adaptive and mutational resistance: role of porins and efflux pumps in drug resistance. Clin Microbiol Rev 25:661–681. CrossRefPubMedPubMedCentralGoogle Scholar
  12. Franke S (2007) Microbiology of the toxic noble metal silver. Mol Microbiol Heavy Met. Springer Berlin Heidelberg, Berlin, pp 343–355CrossRefGoogle Scholar
  13. Franke S, Grass G, Rensing C, Nies DH (2003) Molecular analysis of the copper-transporting efflux system CusCFBA of Escherichia coli. J Bacteriol 185:3804–3812. CrossRefPubMedPubMedCentralGoogle Scholar
  14. Graves JL (2014) A Grain of Salt: metallic and metallic oxide nanoparticles as the new antimicrobials. JSM Nanotechnol Nanomed 2:1–5Google Scholar
  15. Graves JL, Tajkarimi M, Cunningham Q et al (2015) Rapid evolution of silver nanoparticle resistance in Escherichia coli. Front Genet 5:1–13. CrossRefGoogle Scholar
  16. Gudipaty SA, McEvoy MM (2014) The histidine kinase CusS senses silver ions through direct binding by its sensor domain. Biochim Biophys Acta Proteins Proteomics 1844:1656–1661. CrossRefGoogle Scholar
  17. Gudipaty SA, Larsen AS, Rensing C, Mcevoy MM (2012) Regulation of Cu(I)/Ag(I) efflux genes in Escherichia coli by the sensor kinase CusS. FEMS Microbiol Lett 330:30–37. CrossRefPubMedPubMedCentralGoogle Scholar
  18. Gupta A, Matsui K, Lo JF, Silver S (1999) Molecular basis for resistance to silver cations in Salmonella. Nat Med 5:183–188. CrossRefPubMedGoogle Scholar
  19. Gupta A, Phung LT, Taylor DE, Silver S (2001) Diversity of silver resistance genes in IncH incompatibility group plasmids. Microbiology 147:3393–3402. CrossRefPubMedGoogle Scholar
  20. Jacoby GA (2005) Mechanisms of resistance to quinolones. Clin Infect Dis 41:S120–S126. CrossRefPubMedGoogle Scholar
  21. Lee W, Kim K-J, Lee DG (2014) A novel mechanism for the antibacterial effect of silver nanoparticles on Escherichia coli. Biometals 27:1191–1201. CrossRefPubMedGoogle Scholar
  22. Li XZ, Nikaido H, Williams KE (1997) Silver-resistant mutants of Escherichia coli display active efflux of Ag+ and are deficient in porins. J Bacteriol 179:6127–6132. CrossRefPubMedPubMedCentralGoogle Scholar
  23. Lok CN, Ho CM, Chen R, Tam PK, Chiu JF, Che CM (2008) Proteomic identification of the cus system as a major determinant of constitutive Escherichia coli silver resistance of chromosomal origin. J Proteome Res 7:2351–2356. CrossRefPubMedGoogle Scholar
  24. Mchugh GL, Moellering RC, Hopkins CC, Swartz MN (1975) Salmonella typhimurium resistant to silver nitrate, chloramphenicol, and ampicillin. A New Threat in Burn Units? Lancet 305:235–240. CrossRefGoogle Scholar
  25. Mijnendonckx K, Leys N, Mahillon J, Silver S, Van Houdt R (2013) Antimicrobial silver: uses, toxicity and potential for resistance. Biometals 26:609–621. CrossRefPubMedGoogle Scholar
  26. Mizuno T, Shinkai A, Matsui K, Mizushima S (1990) Osmoregulatory expression of porin genes in Escherichia coli: a comparative study on strains B and K-12. FEMS Microbiol Lett 68:289–293. CrossRefGoogle Scholar
  27. Randall CP, Oyama L, Bostock J, Chopra I, O’Neill A (2013) The silver cation (Ag+): antistaphylococcal activity, mode of action and resistance studies. J Antimicrob Chemother 68:131–138. CrossRefPubMedGoogle Scholar
  28. Randall CP, Gupta A, Jackson N, Busse D, O’Neill AJ (2015) Silver resistance in Gram-negative bacteria: a dissection of endogenous and exogenous mechanisms. J Antimicrob Chemother 70:1037–1046. CrossRefPubMedPubMedCentralGoogle Scholar
  29. Salem W, Leitner DR, Zingl FG, Schratter G, Prassl R, Goessler W, Reidl J, Schild S (2015) Antibacterial activity of silver and zinc nanoparticles against Vibrio cholerae and enterotoxic Escherichia coli. Int J Med Microbiol 305:85–95. CrossRefPubMedPubMedCentralGoogle Scholar
  30. Silver S (2003) Bacterial silver resistance: molecular biology and uses and misuses of silver compounds. FEMS Microbiol Rev 27:341–353. CrossRefPubMedGoogle Scholar
  31. Silver S, Phung LT, Silver G (2006) Silver as biocides in burn and wound dressings and bacterial resistance to silver compounds. J Ind Microbiol Biotechnol 33:627–634. CrossRefPubMedGoogle Scholar
  32. Tajkarimi M, Rhinehardt K, Thomas M, Ewunkem JA, Campbell A, Boyd S, Turner D, Harrison SH, Graves JL (2017) Selection for ionic-confers silver nanoparticle resistance in Escherichia coli. JSM Nanotechnol Nanomed 5:1–9Google Scholar
  33. Tan Z, Havell EA, Orndorff PE, Shirwaiker RA (2017) Antibacterial efficacy and cytotoxicity of low intensity direct current activated silver–titanium implant system prototype. Biometals 30:113–125. CrossRefPubMedGoogle Scholar
  34. Xue Y, Davis AV, Balakrishnan G, Stasser JP, Staehlin BM, Focia P, Spiro TG, Penner-Hahn JE, O’Halloran TV (2008) Cu(I) recognition via cation-π and methionine interactions in CusF. Nat Chem Biol 4:107–109. CrossRefPubMedGoogle Scholar

Copyright information

© Springer Nature B.V. 2018

Authors and Affiliations

  1. 1.Instituto Nacional de Tecnología Industrial (INTI)San MartínArgentina
  2. 2.Institute of Food, Nutrition and HealthETH ZurichZurichSwitzerland
  3. 3.HeiQ Materials AGZurichSwitzerland

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