The chemical structure of the free lipid A isolated from MesorhizobiumhuakuiiIFO15243 T was elucidated. Lipid A is a mixture of at least six species of molecules whose struc-tures differ both in the phosphorylation of sugar backbone and in fatty acylation. The backbone consists of ab(1¢fi6) linked 2,3-diamino-2,3-dideoxyglucose (DAG) disaccharide that is partly substituted by phosphate at position 4¢.The aglycon of the DAG-disaccharide has been identified as a-D-galacturonic acid.
