The cell extract of Porphyromonas gingivalis promotes attachment of Prevotella nigrescens cells to hydroxyapatite

Large quantities of Prevotella nigrescens ATCC 25261 (P. nigrescens) cells adhere to hydroxyapatite (HA) treated with extract from Porphyromonas gingivalis 381 (Pg-Ext), but not to HA coated with human serum albumin (HSA) or human serum globulin (HSG). The duration of HA treatment with Pg-Ext and several other conditions were tested to determine the factors causing Pg-Ext to promote P. nigrescens cell adhesion. Pg-Ext adsorbed rapidly to HA in less than 5 min. The maximum adherence of P. nigrescens cells to HA was observed after treatment of HSA and HSG and then retreatment of HA with Pg-Ext. It was found that Pg-Ext heated at 80°C for 30 min did not lose its propensity to promote attachment of P. nigrescens to HA and that it also remained stable at 4°C for at least 6 days. The trypsin-like enzyme activity of Pg-Ext was also measured, with BAPNA as the substrate and commercially purchased trypsin as the standard, and was approximately 0.12 units/mg. These data suggest that the presence of Pg-Ext is one of the essential factors responsible for P. nigrescens cell attachment to apatitic surfaces, and that with its trypsin-like activity, Pg-Ext may be considered an extremely important substance for the establishment of P. nigrescens in the periodontal pocket and the development of periodontal disease. (J. Oral Sci. 45, 99-106, 2003)