Bacterial species-characteristic profiles of molecular species, and the antigenicity of phospholipids and glycolipids in symbiotic Lactobacillus, Staphylococcus and Streptococcus species.

Human symbiotic bacteria, Lactobacillus reuteri (LR) in the intestines, Staphylococcus epidermidis (SE) in skin and Streptococcus salivalis (SS) in the oral cavity, contain dihexaosyl diglycerides (DH-DG) in concentrations equivalent to those of phosphatidyl glycerol (PG) and cardiolipin (CL), together with mono- to tetrahexaosyl DGs. The molecular species, as the combination of fatty acids in the DG moiety, were revealed to be bacterial species-characteristic, but to be similar between glycolipids and phospholipids in individual bacteria, the major ones being 16:0 and cy19:0 for LR, ai15:0 and ai17:0 for SE, and 16:0 and 18:1 for SS, respectively. The carbohydrate structures of DH-DGs were also bacterial species-characteristic, being Galα1-2Glcα for LR, Glcβ1-6Glcβ for SE, and Glcα1-2Glcα for SS, respectively. Also, bacterial glycolipids were revealed to provide antigenic determinants characteristic of bacterial species on immunization of rabbits with the respective bacteria. Anti-L. johnsonii antiserum intensely reacted with tri- and tetrahexaosyl DGs, in which Galα was bound to DH-DG through an α1-6 linkage, as well as with DH-DG from LR. Although anti-SE antiserum preferentially reacted with DH-DG from SE, anti-SS antiserum reacted with DH-DG from SS and, to a lesser extent, with DH-DGs from LR and SE. But, both anti-SE and anti-SS antiserum did not react at all with monohexaosyl DG or glycosphingolipids with the same carbohydrates at the nonreducing terminals. In addition, 75 % of human sera, irrespective of the ABO blood group, were found to contain IgM to tri- and tetrahexaosyl DGs from LR, but not to DH-DGs from LR, SE and SS.