Biologia

Nickel Promotes Biofilm Formation by Escherichia coli K-12 Strains That Produce Curli
Claire Perrin, Romain Briandet, Gregory Jubelin, Philippe Lejeune, Marie-Andrée Mandrand-Berthelot, Agnès Rodrigue and Corinne Dorel Appl. Environ. Microbiol. 2009, 75(6):1723. DOI: 10.1128/AEM.02171-08. Published Ahead of Print 23 January 2009. Downloaded from http://aem.asm.org/ on March 12, 2012 by guestUpdated information and services can be found at: http://aem.asm.org/content/75/6/1723 These include:
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APPLIED AND ENVIRONMENTAL MICROBIOLOGY, Mar. 2009, p. 1723–1733 0099-2240/09/$08.00 0 doi:10.1128/AEM.02171-08 Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Vol. 75, No. 6

Nickel Promotes Biofilm Formation by Escherichia coli K-12Strains That Produce Curli
Claire Perrin,1 Romain Briandet,2 Gregory Jubelin,3 Philippe Lejeune,1 Marie-Andree Mandrand-Berthelot,1 Agnes Rodrigue,1† and Corinne Dorel1†* ´ `
Universite de Lyon F-69622, INSA-Lyon, MAP, CNRS UMR5240, Universite Lyon 1, F-69621 Villeurbanne, France1; ´ ´ INRA-AgroParisTech UMR763, Bioadhesion et Hygiene des Materiaux, 25 Ave. Republique, 91300 Massy, ´ ` ´ ´ France2;and INRA UMR1225, Ecole Nationale Veterinaire de Toulouse, 23 Chemin des Capelles, ´´ 31076 Toulouse Cedex, France3
Received 19 September 2008/Accepted 15 January 2009

Downloaded from http://aem.asm.org/ on March 12, 2012 by guest

The survival of bacteria exposed to toxic compounds is a multifactorial phenomenon, involving well-known molecular mechanisms of resistance but alsoless-well-understood mechanisms of tolerance that need to be clarified. In particular, the contribution of biofilm formation to survival in the presence of toxic compounds, such as nickel, was investigated in this study. We found that a subinhibitory concentration of nickel leads Escherichia coli bacteria to change their lifestyle, developing biofilm structures rather than growing as freefloating cells.Interestingly, whereas nickel and magnesium both alter the global cell surface charge, only nickel promotes biofilm formation in our system. Genetic evidence indicates that biofilm formation induced by nickel is mediated by the transcriptional induction of the adhesive curli-encoding genes. Biofilm formation induced by nickel does not rely on efflux mechanisms using the RcnA pump, as these require a higherconcentration of nickel to be activated. Our results demonstrate that the nickel-induced biofilm formation in E. coli is an adaptational process, occurring through a transcriptional effect on genes coding for adherence structures. The biofilm lifestyle is obviously a selective advantage in the presence of nickel, but the means by which it improves bacterial survival needs to be investigated. Nickelis not well known to the public, since the major use of this metal is in the preparation of alloys. Nickel alloys are known for their superior resistance to both heat and corrosion. These properties make nickel useful in the chemical industry as well as in food processing (storage tanks, piping, etc.). Nickel alloys are also commonly used in medical devices (pacemakers, orthopedic implants,needles, surgical instruments, etc.). One of the major corrosion products of stainless steel is nickel, and bacteria in the surrounding media encounter these metal ions. Nickel alloys are claimed to ensure that the product or implant remains uncontaminated (26). However, increasing evidence shows that bacteria can adhere to any kind of material to develop biofilms, with detrimental consequences. The...