Characterization of coaggregation of Fusobacterium nucleatum PK1594 with six Porphyromonas gingivalis strains.

Coaggregation is a key mechanism in biofilm formation. The aim of this study was to characterize the coaggregation of Fusobacterium nucleatum PK1594 with six Porphyromonas gingivalis strains in terms of kinetics and sugars inhibition. This coaggregation was quantitatively characterized by using a kinetic coaggregation assay. Sugar inhibition profiles were also quantitatively defined. Four types of interactions among these coaggregation partners were found: (1) fast coaggregation that was substantially inhibited by galactose, lactose, and fucose (strain PK1924); (2) fast coaggregation that was not inhibited by any of the sugars tested (strain 274); (3) slow coaggregation that was either substantially or partially inhibited by the sugars mentioned (strains HG405 and W50, respectively); and (4) strains that did not coaggregate with the fusobacteria (ATCC33277 and A7436). These results suggest that adhesin(s) other than the well-known galactose-mediated ones may be involved in coaggregation between F. nucleatum PK1594 and P. gingivalis strains.