Effects of mutating putative two-component systems on biofilm formation by Streptococcus mutans UA159

Streptococcus mutans has at least six pairs of open reading frames that are homologous to bacterial two-component regulatory systems. Putative response regulators from five out of six of these pairs were successfully mutated by insertion of a kanamycin resistance marker and the effects of inactivation of the genes on the ability of the cells to form biofilms in an in vitro model were assessed. Disruption of the response regulators of four systems had no effect on biofilm formation, whereas disruption of one response regulator caused a substantial decrease in biofilm formation as compared to the wild-type S. mutans.