Structure of lipid A from the marine gram-negative bacterium Pseudoalteromonas nigrifaciens IAM 13010T

The structure of lipid A from the marine gamma-proteobacterium Pseudoalteromonas nigrifaciens IAM 13010(T) that was prepared by hydrolysis of the corresponding lipopolysaccharide by acetic acid (1%) was determined by chemical analysis, C-13 NMR spectroscopy, and MALDI/TOF and LSIMS mass spectrometry. It was shown that lipid A is a beta-1,6-bonded disaccharide of glucosamine that is substituted by two phosphoric acids (in the C1 and C4' positions), two (R)-3-hydroxyalkanoic (normal and branched) acids with ester bonding (at the C3 and C3'-positions), and (R)-3-hydroxydodecanoic and (R)-3-dodecanoyloxydodecanoic acids (both with amide bonding at C2' and C2, respectively). It was hypothesized that this type of structure is typical of lipid A from bacteria of the genus Pseudoalteromonas in general.