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Polymyxin B induces lysis of marine pseudoalteromonads

Mart Krupovic1, Rimantas Daugelavicius, Dennis H Bamford

  • 1Department of Biological and Environmental Sciences, 00014 University of Helsinki, Finland.

Antimicrobial Agents and Chemotherapy
|August 22, 2007
PubMed

Insights

Polymyxin B (PMB) antibiotic causes lysis in marine bacteria, unlike growth inhibition in enteric bacteria. This study reveals unique interactions with pseudoalteromonad cell envelopes, requiring high membrane voltage.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Polymyxin B (PMB) is a cationic antibiotic previously limited by side effects.
  • Antibiotic resistance necessitates reevaluating PMB for clinical applications.
  • Previous studies on PMB action focused on enteric bacteria, limiting broader understanding.

Purpose of the Study:

  • To investigate the effects of Polymyxin B on marine pseudoalteromonads.
  • To challenge the assumption that PMB acts uniformly across all bacteria.
  • To elucidate the specific mechanisms of PMB interaction with marine gram-negative bacteria.

Main Methods:

  • Exposure of marine pseudoalteromonads to Polymyxin B.
  • Analysis of bacterial response to PMB, including lysis and cation effects.
  • Assessment of membrane voltage requirements for PMB interaction.

Main Results:

  • Polymyxin B induces cell lysis in pseudoalteromonads, contrasting with growth inhibition in enteric bacteria.
  • High concentrations of divalent cations do not prevent PMB-induced lysis in these marine bacteria.
  • A high membrane voltage is essential for PMB to interact with the cytoplasmic membranes of pseudoalteromonads.

Conclusions:

  • The mechanism of Polymyxin B action varies significantly between bacterial species, challenging the "E. coli as a model" paradigm.
  • Polymyxin B's interaction with marine pseudoalteromonads involves unique cell envelope mechanisms.
  • Understanding these distinct mechanisms is crucial for developing effective antibiotic therapies against resistant gram-negative bacteria.

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