Define microbial antagonism and give an oral example.

Define microbial antagonism and give an oral example.

• A. Antagonism is cooperation
• B. Antagonism is mutualism
• C. Antagonism is commensalism
• D. Antagonism is inhibition of one culture by another; example S. sanguinis producing H2O2 inhibiting S. mutans

Answer: (D)

Microbial antagonism is when one microorganism inhibits or suppresses another, limiting its growth or activity. In the oral environment, a classic example is Streptococcus sanguinis producing hydrogen peroxide, which inhibits Streptococcus mutans. This makes the dental biofilm less cariogenic because S. mutans is a major acid-producing species linked to tooth decay. The other types of relationships described—cooperation, mutualism, or commensalism—do not involve one organism actively suppressing another, so they do not illustrate antagonism.

Microbial antagonism is when one microorganism inhibits or suppresses another, limiting its growth or activity. In the oral environment, a classic example is Streptococcus sanguinis producing hydrogen peroxide, which inhibits Streptococcus mutans. This makes the dental biofilm less cariogenic because S. mutans is a major acid-producing species linked to tooth decay. The other types of relationships described—cooperation, mutualism, or commensalism—do not involve one organism actively suppressing another, so they do not illustrate antagonism.