Psychrophilic and psychrotolerant bacteria are adapted to grow and thrive at cold temperatures (less than 15�C), and are found frequently in marine environments including polar seas and ice.  This work determines the chemical structure of lipid A, the hydrophobic anchor of endotoxin, in psychrophilic and psychrotolerant species of marine bacteria.  As the outer hydrophobic surface in Gram-negative organisms, lipid A is involved in bacterial interactions with and protection from the environment.  We propose that psychrophilic lipid A structures contain constitutive evolutionary differences that support increased outer membrane fluidity at cold temperatures compared to those of related mesophilic bacteria.  In this study MALDI-TOF MS and FAME GC-MS were used to characterize the structure of purified lipid A, and reveal structural evidence of adaptive changes to psychrophilic lipid A.  These structural changes include reduced acyl size and increased acyl variability compared to related mesophilic species, as well as the use of an unusual tetradecadienoyl acyl residue.

Structure and adaptations of lipid A in marine psychrophiles

247th National Meeting (2014)

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