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Chaotropic solutes cause water stress in Pseudomonas putida

Authors

  • John E. Hallsworth,

    Corresponding author
    1. Department of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
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  • Sabina Heim,

    1. Division of Microbiology, GBF – National Research Centre for Biotechnology, Braunschweig, D-38124, Germany.
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  • Kenneth N. Timmis

    1. Department of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK.
    2. Division of Microbiology, GBF – National Research Centre for Biotechnology, Braunschweig, D-38124, Germany.
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E-mail jehalls@essex.ac.uk; Tel. (+44) 1206 872535; Fax (+44) 1206 872592.

Summary

Low water availability is the most ubiquitous cause of stress for terrestrial plants, animals and microorganisms, and has a major impact on ecosystem function and agricultural productivity. Studies of water stress have largely focused on conditions that affect cell turgor, i.e. induce osmotic stress. We show that chaotropic solutes that do not affect turgor reduce water activity, perturb macromolecule–water interactions and thereby destabilize cellular macromolecules, inhibit growth, and are powerful mediators of water stress in a typical soil bacterium, Pseudomonas putida. Chaotropic solute-induced water stress resulted mostly in the upregulation of proteins involved in stabilization of biological macromolecules and membrane structure. Many environmental pollutants and agricultural products are chaotropic chemicals and thus constitute a previously unrecognised but common form of biological stress in water bodies and soils.

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