Structural Analysis of the Deep Rough Lipopolysaccharide from Gram Negative Bacterium Alteromonas macleodii ATCC 27126T: The First Finding of B-Kdo in the Inner Core of Lipopolysaccharides

Alteromonas macleodii ATCC 27126T is a Gram-negative marine bacterium isolated from a sea water sample collected from around the Hawaiian Islands. The structure of the lipooligosaccharide derived from its outer membrane has been fully determined using either alkaline or acid hydrolysis. Alkaline treatment, aimed at recovering the complete carbohydrate backbone, was carried out by mild hydrazinolysis (de-O-acylation) followed by de-N-acylation using hot KOH and furnished a single core glycoform. Mild acid hydrolysis was employed to obtain the lipid A moiety which was selectively de-O-acylated and analysed to determine its primary structure. The structural elucidation of both fractions was carried out by chemical analyses, 2D NMR spectroscopy and MALDI-TOF mass spectrometry and revealed a novel lipooligosaccharide with an unusual structure.