At about what pH do health-associated streptococci stop metabolizing?

At about what pH do health-associated streptococci stop metabolizing?

• A. 5
• B. 6.5
• C. 7
• D. 6

Answer: (D)

Environmental pH strongly regulates bacterial metabolism in dental plaque. Health-associated streptococci are relatively sensitive to acid, so as the environment becomes more acidic, their metabolic activity decreases and they eventually stop metabolizing. This threshold occurs around pH six, where enzyme function and cellular processes become too inhibited for continued sugar fermentation. In the mouth, after sugar intake, plaque pH can dip below this point; these streptococci then pause their metabolism, while more acid-tolerant species can continue to function and drive further acidification if the pH remains low.

Environmental pH strongly regulates bacterial metabolism in dental plaque. Health-associated streptococci are relatively sensitive to acid, so as the environment becomes more acidic, their metabolic activity decreases and they eventually stop metabolizing. This threshold occurs around pH six, where enzyme function and cellular processes become too inhibited for continued sugar fermentation. In the mouth, after sugar intake, plaque pH can dip below this point; these streptococci then pause their metabolism, while more acid-tolerant species can continue to function and drive further acidification if the pH remains low.