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Response of Pseudomonas aeruginosa PAO1 to low shear modelled microgravity involves AlgU regulation

Authors

  • Aurélie Crabbé,

    1. Laboratory of Microbial Interactions, Department of Molecular and Cellular Interactions, Flanders Institute for Biotechnology (VIB), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
    2. Expertise Group Molecular and Cellular Biology, Institute for Environment, Health and Safety, Belgian Nuclear Research Center (SCK·CEN), Boeretang 200, B-2400 Mol, Belgium.
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    • Present addresses: Center for Infectious Diseases and Vaccinology, The Biodesign Institute, Arizona State University, 1001 S. McAllister Avenue, Tempe, AZ 85287, USA;

  • Benny Pycke,

    1. Expertise Group Molecular and Cellular Biology, Institute for Environment, Health and Safety, Belgian Nuclear Research Center (SCK·CEN), Boeretang 200, B-2400 Mol, Belgium.
    2. Laboratory for Microbial Ecology and Technology (LabMET), Ghent University, Coupure Links 653, B-9000 Gent, Belgium.
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    • Center for Environmental Biotechnology, The Biodesign Institute, Arizona State University, 1001 S. McAllister Avenue, Tempe, AZ 85287, USA.

  • Rob Van Houdt,

    1. Expertise Group Molecular and Cellular Biology, Institute for Environment, Health and Safety, Belgian Nuclear Research Center (SCK·CEN), Boeretang 200, B-2400 Mol, Belgium.
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  • Pieter Monsieurs,

    1. Expertise Group Molecular and Cellular Biology, Institute for Environment, Health and Safety, Belgian Nuclear Research Center (SCK·CEN), Boeretang 200, B-2400 Mol, Belgium.
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  • Cheryl Nickerson,

    1. School of Life Sciences, The Biodesign Institute, Center for Infectious Diseases and Vaccinology, Arizona State University, 1001 South McAllister Avenue, Tempe, AZ 85287, USA.
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  • Natalie Leys,

    Corresponding author
    1. Expertise Group Molecular and Cellular Biology, Institute for Environment, Health and Safety, Belgian Nuclear Research Center (SCK·CEN), Boeretang 200, B-2400 Mol, Belgium.
      E-mail nleys@sckcen.be; Tel. (+32) 14 33 27 26; Fax (+32) 14 31 47 93.
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  • Pierre Cornelis

    1. Laboratory of Microbial Interactions, Department of Molecular and Cellular Interactions, Flanders Institute for Biotechnology (VIB), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium.
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E-mail nleys@sckcen.be; Tel. (+32) 14 33 27 26; Fax (+32) 14 31 47 93.

Summary

As a ubiquitous environmental organism that is occasionally part of the human flora, Pseudomonas aeruginosa could pose a health hazard for the immunocompromised astronauts during long-term missions. Therefore, insights into the behaviour of P. aeruginosa under spaceflight conditions were gained using two spaceflight-analogue culture systems: the rotating wall vessel (RWV) and the random position machine (RPM). Microarray analysis of P. aeruginosa PAO1 grown in the low shear modelled microgravity (LSMMG) environment of the RWV, compared with the normal gravity control (NG), revealed an apparent regulatory role for the alternative sigma factor AlgU (RpoE-like). Accordingly, P. aeruginosa cultured in LSMMG exhibited increased alginate production and upregulation of AlgU-controlled transcripts, including those encoding stress-related proteins. The LSMMG increased heat and oxidative stress resistance and caused a decrease in the oxygen transfer rate of the culture. This study also showed the involvement of the RNA-binding protein Hfq in the LSMMG response, consistent with its previously identified role in the Salmonella LSMMG and spaceflight response. The global transcriptional response of P. aeruginosa grown in the RPM was highly similar to that in NG. Fluid mixing was assessed in both systems and is believed to be a pivotal factor contributing to transcriptional differences between RWV- and RPM-grown P. aeruginosa. This study represents the first step towards the identification of virulence mechanisms of P. aeruginosa activated in response to spaceflight-analogue conditions, and could direct future research regarding the risk assessment and prevention of Pseudomonas infections during spaceflight and in immunocompromised patients.

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