Interactions between and within Streptococcus mutans and Streptococcus sobrinus isolated from humans harboring both...

Area of Science:

• Microbiology
• Oral Health
• Bacteriology

Background:

• Streptococcus mutans and Streptococcus sobrinus are key cariogenic bacteria.
• Understanding their interactions is crucial for dental caries prevention.
• Bacteriocin production plays a role in bacterial community dynamics.

Purpose of the Study:

• To examine the prevalence and bacteriocin-mediated interactions of Streptococcus mutans and Streptococcus sobrinus.
• To investigate inter- and intra-species interactions within dental plaque.
• To assess the influence of sucrose on bacteriocin activity.

Main Methods:

• Analysis of plaque samples from buccal tooth surfaces of seven subjects.
• Isolation and identification of Streptococcus mutans and Streptococcus sobrinus strains.
• Bacteriocin activity testing using the stab inoculation technique.
• Evaluation of interactions with glucose and sucrose as medium components.

Main Results:

• Non-uniform colonization of tooth surfaces by Streptococcus mutans and Streptococcus sobrinus.
• Varied interspecies proportions and absence of bacteriocin interactions within the same species on a single tooth.
• Higher bacteriocin inhibition ability observed for strains isolated from plaque compared to saliva.
• Streptococcus mutans demonstrated greater bacteriocinogenicity than Streptococcus sobrinus.
• Sucrose enhanced Streptococcus mutans' bacteriocin activity against conspecifics but reduced it against Streptococcus sobrinus.

Conclusions:

• Bacteriocin production and interactions are complex and site-specific within the oral cavity.
• Streptococcus mutans appears to be a more potent bacteriocin producer than Streptococcus sobrinus.
• Dietary factors like sucrose can modulate bacteriocin activity, impacting bacterial competition.