Ecological Relationship between Lactobacillus acidophilus and Periodontopathic Bacteria

Objectives: To investigate the ecological relationship between Lactobacillus acidophilus and representative periodontopathic bacteria in mixture culture. Methods: 1ml suspensions (1x10³ml^-1)of Lactobacillus acidophilus (La, ATCC 4356)were mixed with equal volume and concentration of Porphyromonas gingivalis (Pg, ATCC 33277), Actinobacillus actinomycetemcomitans (Aa, Y4) or Fusobacterium nucleatum (Fn, ATCC 10953) respectively. All mixtures were cultured under anaerobic conditions at 37°C for 12h, 24h and 48h, and 2ml of each bacteria cultured alone as control. The CFU of each culture at different time was counted and the corresponding pH values were measured with PHS-3C pH meter. All experiments were performed in triplicate. The results were analysed with ANOVA. Results: The amounts of Pg,Aa or Fn cultured with La significantly decreased compared with those culture alone (P<0.01or P<0.001), while La amounts increased significantly at 12h and 24h (P<0.01)and exhibited no significant difference at 48h compared with La culture alone (P>0.05). The pH values of mixture culture were lower than those of Pg, Aa or Fn culture alone (P<0.01), and was no significant difference compared with La cultrue alone (P>0.05). Conclusion: La strongly inhibited the growth of Pg, Aa or Fn. The new strategy of confining periodontal pathogens with La as ecological modulator or periodontal replacement therapy was worthy of further study.