Collectively, these results indicate that, in contrast to other Streptococcus species, the S. mutans Opp system, and particularly the OppA protein, does not represent an important trait required for growth and colonization.

glutamate to the media suggesting that uptake of these amino acids is essential for S. mutans. These data showed also that the two uptake system share similar functions regarding uptake of these amino acids. The KG1 strain showed also an enhanced capability to bind abiotic surfaces adhesion (polystyrene plaques), suggesting an increased biofilm formation with regard to the parental strain. On the other hand, the mutant deleted in the gln operon showed higher capacity to biding n-hexadecan suggesting an altered hydrophobic profile of surface-exposed components. The results demonstrated, for the first time, that both operons are involved with the uptake of glutamine and glutamate in S. mutans. Furthermore, our data indicate that the two uptake systems may play different roles on the virulence of S. mutans.