In Vitro Anti-Biofilm and Antibacterial Properties of Streptococcus downii sp. nov

The aim of this study was to evaluate the potential anti-biofilm and antibacterial activities of sp. nov. To test anti-biofilm properties, and were grown in a biofilm model in the presence or not of sp. nov. for up to 120 h. For the potential antibacterial activity, 24 h-biofilms were exposed to sp. nov for 24 and 48 h. Biofilms structures and bacterial viability were studied by microscopy, and the effect in bacterial load by quantitative polymerase chain reaction. A generalized linear model was constructed, and results were considered as statistically significant at < 0.05. The presence of sp. nov. during biofilm development did not affect the structure of the community, but an anti-biofilm effect against was observed ( < 0.001, after 96 and 120 h). For antibacterial activity, after 24 h of exposure to sp. nov., counts of ( = 0.019) and ( = 0.020) were significantly reduced in well-structured biofilms. Although moderate, anti-biofilm and antibacterial activities of sp. nov. against oral bacteria, including some periodontal pathogens, were demonstrated in an in vitro biofilm model.