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Biofilm susceptibility to metal toxicity

Authors

  • Joe J. Harrison,

    1. Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
    2. Biofilm Research Group, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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  • Howard Ceri,

    Corresponding author
    1. Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
    2. Biofilm Research Group, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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  • Carol A. Stremick,

    1. Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
    2. Biofilm Research Group, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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  • Raymond J. Turner

    Corresponding author
    1. Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4.
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*E-mail turnerr@ucalgary.ca; Tel. (+1) 403 220 4308; Fax (+1) 403 289 9311 or e-mail ceri@ucalgary.ca; Tel. (+1) 403 220 6960; Fax (+1) 403 289 9311.

Summary

This study compared bacterial biofilm and planktonic cell susceptibility to metal toxicity by evaluating the minimum inhibitory concentration (MIC), the planktonic minimum bactericidal concentration (MBC), and minimum biofilm eradication concentration (MBEC) using the MBEC™ device. In total, 17 metal cations and oxyanions, chosen to represent groups VIB to VIA of the periodic table, were each tested on biofilm and planktonic cultures of Escherichia coli JM109, Staphylococcus aureus ATCC 29213, and Pseudomonas aeruginosa ATCC 27853. In contrast to control antibiotic assays, where biofilm cultures were 2 to 64 times less susceptible to killing than logarithmically growing planktonic bacteria, metal compounds killed planktonic and biofilm cultures at the same concentration in the vast majority of combinations. Our data indicate that, under the conditions reported, growth in a biofilm does not provide resistance to bacteria against killing by metal cations or oxyanions.

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