Which bacteria are commonly studied as pioneers in dental plaque formation and can influence community assembly?

Which bacteria are commonly studied as pioneers in dental plaque formation and can influence community assembly?

• A. Streptococcus mutans and Lactobacillus acidophilus
• B. Streptococcus sanguinis and Actinomyces naeslundii
• C. Porphyromonas gingivalis and Tannerella forsythia
• D. Veillonella parvula and Fusobacterium nucleatum

Answer: (B)

Early colonizers are the bacteria that first attach to the tooth surface and begin forming the dental plaque, setting up the environment for all that follows. Streptococcus sanguinis is a classic pioneer because it readily binds to the salivary pellicle on enamel and can coaggregate with other early settlers, establishing the initial layer of the biofilm. Actinomyces naeslundii also arrives early, attaching to the tooth surface and interacting with neighboring pioneers to help build the foundational matrix that supports subsequent microbes. Together, these organisms shape which species can join later, influence the organization of the community, and steer the succession of plaque development.

The other pair usually involves organisms associated with later stages of plaque or with periodontal disease-associated biofilms. Late colonizers and bridging species come in after the initial layer is established, and thus do not best illustrate the concept of pioneers setting the stage for community assembly.