Dental biofilms are complex and consists of many different species which can interact with each other and affect virulence properties. In this study we investigated the effect of Parvimonas micra on proteolytic activity in a multi-species bacterial consortium.
Multispecies consortia were constructed, with and without P. micra, using the following species: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Actinomyces naeslundii, P. micra, Streptococcus oralis, Streptococcus mitis, Streptococcus gordonii and Streptococcus cristatus. The bacteria were grown anaerobically in 10% serum. Proteolytic activity was measured after 24h and 7 days using fluorogenic substrate, BIKKAM-10 specific for gingipains. The gingipain activity was expressed as relative fluorescent units/min/107 cells. In addition, the effect of supernatants from over-night grown P. micra on gingipain activity was investigated in a single species P. gingivalis model.
After 24h the gingipain activity in the consortium was low and there was no significant difference between the two consortia. However after 7 days, the gingipain activity was 7-fold higher in the consortium with P. micra present. Twenty-four hour exposure of P. gingivalis to P. micra supernatants resulted in a 3-fold increase in gingipain activity compared to control cells.
The presence of P. micra enhance the activity of P. gingivalis gingpains. Further studies revealed that secernated products of P. micra were involved.