Abstract:

Objective　To preliminarily investigate the relationship between the Lactate dehydrogenase (LDH) activity ofStrep- tococcus mutans(S.mutans)and dental caries initiation.Methods　100S. mutansstrains derived from caries-active and caries- free individuals were cultured in BHI medium supplemented with glucose. Cells were extracted and ruptured, and the extracted liquid proteinwas quantifiedwith Coomassie brilliant blue G250 stainingmethods. LDHactivitywas assayed usingthe pyruvate-de- pendent oxidation of NADH-with and without FDP.Results　LDH activity of the two groups strains had no difference (P> 0·05), but the distribution of differ class enzyme activity strains in the two groups was different (P<0·05).Conclusion　LDH activity ofS.mutansis correlated to the initiation of dental caries to some extent. The measurement methods in this study can be applied in preliminary quantitation of LDH activity and the screening ofS.mutansstrains.

Key words: Streptococcus mutans, lactate dehydrogenase, protein quantitation, enzyme activity