Structural investigation on the lipooligosaccharide fraction of psychrophilic Pseudoalteromonas haloplanktis TAC 125 bacterium.

The core structure of the cell-wall lipooligosaccharide (LOS) fraction of an Antarctic Gram-negative bacterium, Pseudoalteromonas haloplanktis TAC 125 strain, was determined to be deacetylated alditols. These were obtained from native LOS fraction by O-deacylation, dephosphorylation, reduction and finally N-deacylation. Two novel structures were detected, the more highly represented molecule consisting of the following hexasaccharide chain: α‐d‐ManpNH₂-(1→3)‐β‐d‐Galp-(1→4)‐α‐l‐glycero‐d‐manno‐Hepp‐(1→5)‐α‐d‐Kdo‐(2→6)‐β‐d‐GlcpNH₂‐(1→6)‐d‐GlcNH₂(ol) while the corresponding pentasaccharide, lacking the ManpNH₂ residue, was less abundant. To the best of our knowledge, the structural investigation presented here, mainly performed by NMR and MS methods, is the first report of the lipopolysaccharide fraction of a psychrophilic bacterium. [ABSTRACT FROM AUTHOR]