Microbiology And Immunology 6400 Oral Intermicrobial Interactions Practice Test

In the oral biofilm, pH is shaped not only by acid production but also by organisms that remove acids from the environment. Veillonella stands out because it uses lactic acid as its main carbon source, converting it to weaker end products like propionate and acetate. By taking up lactate, it lowers the concentration of free hydrogen ions available, thereby buffering the pH and mitigating acidification caused by other bacteria. The others listed tend to be major acid producers. S. mutans ferments sugars to lactic acid, driving pH down and promoting demineralization. Lactobacillus also produces lactic acid and contributes to cariogenicity. Actinomyces can ferment carbohydrates and generate acids, but they do not primarily act as lactate consumers to buffer the environment. Thus, Veillonella best fulfills the role of buffering the pH in the oral environment through lactate utilization.