A dual-species microbial model for studying the dynamics between oral streptococci and periodontal pathogens during biofilm development on titanium surfaces by flow cytometry.

The association of the pioneer organisms Streptococcus mutans ATCC 25175 or Streptococcus oralis ATCC 9811 with secondary colonizers Fusobacterium nucleatum ATCC 25586 or Porphyromonas gingivalis ATCC 33277 during biofilm development on titanium surfaces was evaluated by flow cytometry (FCM) using specific polyclonal antibodies. ELISA and FCM were employed, revealing high antibody sensitivity and specificity. Biofilm formation of four dual-species combinations was analyzed by crystal violet staining, while the association between streptococci and periodontal pathogens was assessed using FCM. Dual-species association between S. oralis and P. gingivalis or F. nucleatum showed a proportional decrease in S. oralis during biofilm development, with a concomitant increase in P. gingivalis or F. nucleatum. This trend was not observed in either of the dual-species associations of S. mutans with the periodontal pathogens. Our dual-species microbial model, which employed FCM, proved to be useful in the study of partnerships between bacteria in oral associations, showing that the presence of primary colonizers is required for the establishment of secondary colonizers in biofilms. The proposed experimental approach is technically simple to prepare and analyze, and also proved to be reproducible; hence, it is well-suited for investigating the development and dynamics of oral communities.