Comparative studies of the outer membranes of Bacteroides gingivalis, strains ATCC 33277, W50, W83, 381.

Outer membrane fractions from Bacteroides gingivalis strains ATCC 33277, 381, W50, and W83 were isolated by French pressure cell disruption and the distribution of major and minor proteins was determined by SDS-PAGE electrophoresis after treatment with 2% Sarkosyl and 2% Triton X-100. Heat-modifiability of the outer membrane proteins (OMPs) from these B. gingivalis strains was also determined after treatment at 100 degrees C and analysis by both 1- and 2-dimensional SDS-PAGE. The distribution of the OMPs on the surface of these B. gingivalis strains was determined by 125I labelling. For the most part of the OMPs of B. gingivalis presented a complex distribution, with OMPs observed between 123 kD and 13 kD. While the distribution of the OMPs was strain specific, OMPs common to all of the strains were observed. Two percent Sarkosyl treatment of the OMs at room temperature resulted in the solubilization of approximately 60% of the OMP. The Sarkosyl-insoluble MOMPs had relative molecular weights between 110 kD and 20 kD. Many of the OMPs which were separated at room temperature were heat-modified at either 65 degrees C or 100 degrees C. Heating of the OMs at 100 degrees C resulted in the heat modification of the majority of those OMPs observed at room temperature. Sarkosyl-100 degrees C OMs displayed MOMPs at apparent molecular weights between 90 kD and 15 kD. Radioiodination of the B. gingivalis strains ATCC 33277, 381, W83 and W50 revealed between 7 and 14 MOMPs at the cell surface depending upon the strain. The complexity of the OM of these B. gingivalis strains indicated the possibility of identifying and separating those OMPs involved in a variety of biological functions, including virulence, transport, and cell interaction.