"Structural characterization of the Lipid A from the LPS of the haloalkalophilic bacterium Halomonas pantelleriensis" in its current form for publication in the Extremophiles

Halomonas pantelleriensis is a Gram-negative haloalkaliphilic bacterium isolated from the sand of the volcanic Venus mirror lake, closed to seashore in the Pantelleria island in the south of Italy. It is able to optimally grow in media containing 3-15% (w/v) total salt and at pH between 9-10. To survive in these harsh conditions the bug has developed several strategies that probably concern the bacteria outer membrane, a barrier regulating the exchange with the environment. In such a context the lipopolysaccharides (LPSs), which are among the major constituent of the Gram-negative outer membrane, are thought to contribute to the restrictive membrane permeability properties. The structure of the lipid A family derived from the lipopolysaccharide of Halomonas pantelleriensis is reported herein. The lipid A was obtained from the purified LPS by mild acid hydrolysis. The lipid A, which contains different number of fatty acids residues, and its partially deacylated derivatives were completely characterized by means of ESI FT-ICR mass spectrometry and chemical analysis. A comparison with the lipid A structure of the phylogenetic proximal Halomonas magadiensis is also reported.