Table 1.

Acid-adaptive response of S. mutans UA159 and SM11

StrainGrowth pH1-h glycolytic pH (final pH)aATPase activity (nmol of PO4/mg [dry wt])b
UA1597.03.303 (±0.08)0.0578 (±0.0062)
5.03.208 (±0.111)0.2429 (±0.0658)
SM117.03.562 (±0.107)0.0689 (±0.0103)
5.03.33 (±0.075)0.1862 (±0.062)
  • a Differences in the final pH reached from pH 7-grown cells were statistically significant ( P < 0.05 ). Although the differences in the final glycolytic pH values achieved by pH 5-grown cells of UA159 and SM11 were not statistically significant, because of day-to-day variation in the final pH values achieved by a given strain (about 0.1 pH unit), in every instance, the mutant was never able to lower the pH as low as the wild-type strain.

  • b ATPase activity is expressed as the amount of PO4 liberated 30 min after the addition of ATP. The results presented here are the means and standard deviations of three independent experiments.