Abstract:

BACKGROUND: Studies have found that the exogenous bis-(3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP) can inhibit biofilm formation of staphylococcus aureus in a dose-dependent manner.
OBJECTIVE: To investigate the effect of c-di-GMP on biofilm formation of Streptococcus mutans.
METHODS: Different concentrations of exogenous c-di-GMP (0, 2, 20, 200, 400 µmol/L) were acted on Streptococcus mutans biofilms for 48 hours. Absorbance value was measured by using microplate reader. Changes of biofilms formation were observed. Similar volumes of normal saline were added as negative control. At the meantime, Streptococcus mutans biofilms formed in vitro on fresh enamel discs of extraction tooth were also acted on with the concentration of 200 μmol/L c-di-GMP and normal saline for   48 hours respectively and observed under scanning electron microscope.
RESULTS AND CONCLUSION: The biofilm formation of the Streptococcus mutans was significantly inhibited in the presence of c-di-GMP as compared with the negative control group. When the concentration of c-di-GMP was 200 μmol/L, the biofilm formation ability of the Streptococcus mutans decreased by 65% and when the concentration was 400 μmol/L, the biofilm formation ability was almost inhibited (P < 0.05). Results of scanning electron microscope showed that Streptococcus mutans were not regularly and the extra cellular polysaccharide was reduced with the pulsing of c-di-GMP. It is showed that c-di-GMP can inhibit the biofilm formation ability of Streptococcus mutans.