Evaluation of Predation Capability of Periodontopathogens Bacteria by Bdellovibrio Bacteriovorus HD100. An in Vitro Study

Treatment options against periodontitis attempt to completely remove oral microbiota even if several species in dental plaque demonstrate protective features. Predatory bacteria that selectively predate solely on Gram-negative bacteria might be a viable therapeutic alternative. Therefore, the aim of this study is to in vitro evaluate the susceptibility of some oral pathogens to predation by B. bacteriovorus HD100 in liquid suspension. Cultures of prey cell were prepared in brain heart infusion broth (BHI) broth incubating overnight at the appropriate conditions for each organism to reach log phase of growth. Predatory activity was assessed by measuring optical density at 600 nm after 12, 24, 48 and 72 hours. Statistical analysis was performed using the Mann-Whitney U test and p values less than 0.05 were considered statistically significant. The study demonstrated that B. bacteriovorus is able to predate on aerobic species and on microaerophilic ones (p < 0.05) but also that its predatory capacity is strongly compromised by the conditions of anaerobiosis. B. bacteriovorus, in fact, was unable to predate the anaerobic species involved in the present study (F. nucleatum and P. gingivalis). The findings of the study suggest that B. bacteriovorus is able to tolerate microaerophilic conditions and that in anaerobiosis it cannot exert its predatory capacity. Such evidence could lead to its use as an agent to prevent recolonization of the periodontal pocket following therapy. Further studies are needed to investigate the activity of B. bacteriovorus against recently recognized periodontopathogens, alone or organized in biofilms of multi-species communities.