Abstract:

Objective

To investigate the efficacy of ldh-luc reporter strain of Streptococcus mutans （S.mutans）， which was constructed in our previous study， and to probe the metabolic status of the reporter strain of S.mutans growing as either in a planktonic culture or a in biofilm community.

Methods

Growth curve， scanning electron microscope （SEM） and colony-forming units （CFU） counts were used to investigate the metabolic status of the reporter strain and the wide type of S.mutans growing as either in a planktonic culture or in a biofilm community. The fluorescence activity of this reporter strain was also measured.

Results

Growth curves and CFU counts of the reporter strain and the wide type of S.mutans were similar. There was no significant difference between the 4， 12 and 24 h biofilm of the reporter strain and the wide type of S.mutans by SEM. The fluorescence expression of the report strain was steady from exponential phase to stationary phases. The RLU reflected the amount of live S.mutans.

Conclusions

The growth abilities of the reporter strain were similar with the wide type of S.mutans. And the fluorescence activity of this reporter strain was stable. All of these results suggested that the reporter strain could be used to probe the metabolic status of S.mutansand response of S.mutans to antimicrobial agents instead of the wild type.

Key words: S.mutans, ldh-luc reporter strain, Growth curve, Biofilm, Fluorescence activities