Bacteriocins are used by many oral streptococci to combat other species in the oral cavity. Which species is explicitly named as containing bacteriocins?

Bacteriocins are used by many oral streptococci to combat other species in the oral cavity. Which species is explicitly named as containing bacteriocins?

• A. Streptococcus pneumoniae
• B. Streptococcus mutans
• C. Streptococcus pyogenes
• D. Streptococcus faecalis

Answer: (B)

Bacteriocins are small antimicrobial peptides produced by bacteria to inhibit closely related species, giving producers a competitive edge in crowded niches like dental plaque. In the oral environment, Streptococcus mutans is well known to produce mutacins—named bacteriocins that target competing streptococci and other bacteria—helping S. mutans establish and maintain its position in the biofilm associated with caries. Because the question asks which species is explicitly named as containing bacteriocins, Streptococcus mutans fits best, since mutacins are a defined, named class of bacteriocins produced by this species. The other listed species can have various virulence factors, but they are not singled out in standard references as having a named bacteriocin family like mutacins in the oral context.

Bacteriocins are small antimicrobial peptides produced by bacteria to inhibit closely related species, giving producers a competitive edge in crowded niches like dental plaque. In the oral environment, Streptococcus mutans is well known to produce mutacins—named bacteriocins that target competing streptococci and other bacteria—helping S. mutans establish and maintain its position in the biofilm associated with caries. Because the question asks which species is explicitly named as containing bacteriocins, Streptococcus mutans fits best, since mutacins are a defined, named class of bacteriocins produced by this species. The other listed species can have various virulence factors, but they are not singled out in standard references as having a named bacteriocin family like mutacins in the oral context.