Microbiology and Immunology 6400 Oral Intermicrobial Interactions Practice Test

Arginine metabolism in dental plaque is largely driven by the arginine deiminase pathway, which converts arginine into citrulline and ornithine while releasing ammonia. This ammonia helps neutralize acid in the plaque environment, giving a buffering effect that many bacteria rely on to survive acidic conditions.

The dental plaque streptococci are among the most abundant organisms in plaque and are well known to possess this arginolytic pathway, making them the primary contributors to arginine catabolism in the biofilm. That abundance and metabolic capability makes them the best fit for identifying the group that dominates arginine utilization.

Lactobacilli, while important acid producers associated with caries progression, are not the main arginine utilizers. Actinomyces can metabolize arginine but are less abundant than the dominant plaque streptococci. Candida is a yeast and not the principal arginine-catabolizing organism in dental plaque.