Abstract
An outer membrane complex containing hemagglutinating and bacterial aggregating activity has been isolated from Bacteroides gingivalis. Examination of the membrane material by biochemical analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunological means revealed that the crude outer membrane preparation contained three major proteins and a lipopolysaccharide population that displayed size heterogeneity. At least two membrane proteins as well as the lipopolysaccharide were found to be antigenically active by immunoblot analysis. With gel chromatography and a lipopolysaccharide disaggregating buffer the membrane material was separated into two fractions. An accompanying separation of the two adherence activities was observed. The first membrane fraction, containing mostly protein and carbohydrate material, was found to contain the bacterial aggregating activity. This fraction also contained a high-molecular-weight lipopolysaccharide population. The second membrane fraction, consisting of low-molecular-weight lipopolysaccharide, protein, and loosely bound lipid was found to contain the hemagglutinating activity.