Disruption Potential of a Multi-species Oral Biofilm by Probiotics: PreliminaryInvestigation of a New Bacillus subtilis Strain

Probiotics may represent an appropriate alternative to oral therapy by specifically targeting pathogens during the successive phases of biofilm “formation”. The aim of this work was to find ways to complement and strengthen this anti-biofilm action through examining the effects of 13 probiotics on the “preformed” three-dimensional biofilm structure. An in vitro dental multi-species biofilm model has been developed using pioneer-colonizing streptococci strains Streptococcus mutans, Streptococcus sobrinus, and Streptococcus oralis subsp. oralis with the addition of Actinomyces naeslundii, to obtain highly heterogeneous strong biofilm architecture. Among the different probiotic genera tested, only the genus Bacillus had a significant disruptive impact on biofilm. B. subtilis NOH (Natto Original Habitat) isolated from a traditional Japanese fermented food (natto) was the most effective disrupter, able to destroy 39% of pre-formed biofilm. Some results have suggested the presence of biosurfactants in its supernatant. Unlike B. subtilis NOH, the B. subtilis CU1 (CNCM I-2745) strain showed strong antibacterial properties against pathogenic organisms and blocked biofilm development at high probiotic concentration. A dual strategy of applying agents with disruptive (B. subtilis NOH) and antimicrobial (B. subtilis CU1) activity could be an interesting approach, with disassembling of the matrix structure exposing pathogenic organisms to more efficient killing.