The outer leaflet of the outer membrane of Gram-negative bacteria is composed mainly of lipid A, the anchor and primary component of endotoxin.  Psychrophilic bacteria thrive in cold marine environments, through adaptation to optimal growth at cold temperatures below 15�C and survival below 0�C.  It is the hypothesis of this work that adaptation to these cold conditions involves constitutive structural changes to lipid A, in particular the use of shorter acyl residues and/or more unsaturation than that found in closely related mesophiles.  This work examines the lipid A structures of two psychrophiles using chromatography, mass spectrometry, chemical degradation analysis, and comparison to the structures of related mesophilic bacteria.  Mass spectrometry of purified lipid A demonstrates predominant use of short acyl residues and an unusual degree of acyl variation in Psychrobacter cryohalolentis, and a more homogenous structure with unsaturated acyl residues in Psychromonas marina.  (USNA NARC, DoD DTRA)

Structure and adaptations of endotoxin in psychrophiles

243rd National Meeting (2012)

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