Congo red binding by Porphyromonas gingivalis is mediated by a 66 kDa outer-membrane protein

Article Abstract:

SDS-PAGE analysis of whole cells of strains of Porphyromonas gingivalis W50, HG184, HG189, WPH35, the avirulent mutant W50 BE1 and the brown pigmenting colonial variant W50 BR1, and Porphyromonas asaccharolytica B535 and Porphyromonas endodontalis HG370 reveals that Congo-red binding to these cells is facilitated by a minor outer membrane protein of 66 kDa. The Congo-red binding element that is related to a Coomassie-blue-stained band is present in the outer membrane in both haemin-restricted and haemin-abundant conditions. Addition of 2 moles of ammonium sulphate increases the binding while polymoxin B pre-treatment does not influence it, indicating the participation of non-specific hydrophobic interactions. Papain, trypsin and 8-anilino-1-naphthalenesuphonic acid suppress the binding.

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Modulation of antibacterial peptide activity by products of Porphyromonas gingivalis and Prevotella spp

Article Abstract:

The ability of anaerobic periodontal bacteria to inactivate and resist killing by antimicrobial peptides through production of extracellular proteases has been investigated. To this end, antibacterial activities of peptides were analyzed in a double-layer agarose diffusion assay, while MICs and MBCs were identified in broth microdilution assays. Results show that culture supernates of Porphyromonas gingivalis and Prevotella spp inactivated mastoparan, magainin II and cecropin B while Gram-positive oral supragingival bacteria had no effect.

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Development of a steady-state oral microbial biofilm community using the constant-depth film fermenter

Article Abstract:

Biofilm formation in a nine-membered community of oral bacteria grown to steady state in an anaerobically-incubated chemostat is investigated using a constant-depth film fermenter (CDFF). The bacteria is transferred from the chemostat to the CDFF, which is incubated aerobically. Results indicate succession during biofilm formation. Electron microscopy shows evidence of spatial differentiation in bacteria near the upper surface and those confined to the middle portion of the CDFF.

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