Studies on the binding of bacteria to glycolipids. Two species of Propionibacterium apparently recognize separate epitopes on lactose of lactosylceramide.

Two species of Propionibacterium were analysed regarding their binding to glycosphingolipids. Bacteria were labeled with 125I and selective interaction with glycolipids on thin-layer chromatograms was revealed by autoradiography. The carbohydrate site in common for active molecular species appeared to be lactose. The two bacteria differed, however, in the overall binding pattern on the chromatogram, probably due to recognition of separate epitopes on lactose. P. freudenreichii bound only to lactosylceramide while P. granulosum also recognized substituted lactosylceramide: Gal alpha 1----3Gal beta 1----4Glc beta Cer, GlcNAc beta 1----3Gal beta 1----4Glc beta Cer and Gal beta 1----3GlcNAc beta 1----3Gal beta 1----4Glc beta Cer were active, but Gal-alpha 1----4Gal beta 1----4Glc beta Cer was inactive. Also, there was an interesting dependence on ceramide structure in the case of lactosylceramide. P. freudenreichii bound to lactosylceramide with sphingosine and non-hydroxy fatty acids but not to species with sphingosine and 2-hydroxy fatty acids, phytosphingosine and non-hydroxy fatty acids or phytosphingosine and 2-hydroxy fatty acids. For P. granulosum the situation was reversed. This may be explained by an influence of ceramide structure on the presentation of the two lactose epitopes at the assay surface. These results were supported by curves from the binding of labeled bacteria to glycolipids coated in microtiter wells and in part by binding to glycolipid-coated chicken erythrocytes.