, Volume 4, Issue 2, pp 77–82

Heavy metal-resistant bacteria as extremophiles: molecular physiology and biotechnological use of Ralstonia sp. CH34

  • D. H. Nies

DOI: 10.1007/s007920050140

Cite this article as:
Nies, D. Extremophiles (2000) 4: 77. doi:10.1007/s007920050140


In contrast to thermophilic or psychrophilic organisms, heavy metal-resistant bacteria do not supply enzymes that are active under harsh conditions, but are themselves tools for the evaluation and remediation of heavy metal-contaminated environments. Ralstonia sp. CH34 is a gram-negative bacterium with a remarkable set of resistance determinants, allowing this bacterium to live in extreme environments that are heavily contaminated with toxic metal ions. These heavy metal ions are mostly detoxified by inducible ion efflux systems that reduce the intracellular concentration of a given ion by active export. Because all metal resistance determinants in this bacterium are inducible, their regulatory systems can be used to develop biosensors that measure the biologically important concentrations of heavy metals in an environment. Resistance based on metal ion efflux detoxifies only the cytoplasm of the respective cell. Therefore, this resistance mechanism cannot be used directly to develop biotechnological procedures; however, metal ion efflux can protect a cell in a metal-contaminated environment. Thus, the cell can be enabled to mediate biochemical reactions such as precipitation of heavy metals with the carbon dioxide produced during growth or degradation of xenobiotics.

Key words Heavy metal bioprecipitation Heavy metal biosensors Heavy metal resistance Cadmium Cobalt Zinc Nickel Chromate Ralstonia 

Copyright information

© Springer-Verlag Tokyo 2000

Authors and Affiliations

  • D. H. Nies
    • 1
  1. 1.Institut für Mikrobiologie, Martin-Luther-Universität, Halle-Wittenberg, Kurt-Mothes-Str. 3, D-06099 Halle, Germany Tel. +49-345-5526352; Fax +49-345-5527010 e-mail: d.nies@mikrobiologie.uni-halle.deDE

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