Background SCH-79797 was recently shown to be a broad-spectrum antibacterial agent with a dual-bactericidal mechanism. However, its anti-biofilm effect remains unknown. Purpose To investigate the effect of SCH-79797 on the biofilm formation of the cariogenic Streptococcus mutans Methods and Results Crystal violet staining, colony forming units count and MTT assays (for cell metabolic activity) revealed that S. mutans biofilm formation was significantly suppressed. In addition, virulence factors, including extracellular polysaccharides (investigated by bacterial/exopolysaccharide staining and the anthrone method) and acid production (investigated by lactic acid and supernatant pH detection) were also inhibited significantly. Moreover, the biofilm inhibitory effect of SCH-79797 was mediated through its repression of bacterial growth and not by a bactericidal effect, which was verified by growth curve and bacterial live/ dead staining, respectively. Quantitative real-time PCR results disclosed that SCH-79797 affected bacterial acid production and tolerance, polysaccharide synthesis and remodeling, biofilm formation and quorum sensing-related gene expression. In addition, SCH-79797 showed good biocompatibility as determined by cytotoxicity assays. Conclusion SCH-79797 had an anti-biofilm effect and showed application prospects in the control of dental caries.

Background To investigate the effect of ficin, a type of proteases, on Candida albicans (C. albicans) biofilm, including forming and pre-formed biofilms. Methods Crystal violet tests together with colony forming unit (CFU) counts were used to detect fungal biofilm biomass. Live/dead staining of biofilms observed by confocal laser scanning microscopy was used to monitor fungal activity. Finally, gene expression of C. albicans within biofilms was assessed by qRT-PCR. Results According to our results, biofilm biomass was dramatically reduced by ficin in both biofilm formation and pre-formed biofilms, as revealed by the crystal violet assay and CFU count (p < 0.05). Fungal activity in biofilm formation and pre-formed biofilms was not significantly influenced by ficin according to live/dead staining. Fungal polymorphism and biofilm associated gene expression were influenced by ficin, especially in groups with prominent antibiofilm effects. Conclusions In summary, ficin effectively inhibited C. albicans biofilm formation and detached its preformed biofilm, and it might be used to treat C. albicans biofilm associated problems.

BackgroundDental caries is one of the oldest and most common infections in humans. Improved oral hygiene practices and the presence of fluoride in dentifrices and mouth rinses have greatly reduced the prevalence of dental caries. However, increased fluoride resistance in microbial communities is concerning. Here, we studied the effect of fluoride-resistant Streptococcus mutans (S. mutans) on oral microbial ecology and compare it with wild-type S. mutans in vitro.MethodsBiofilm was evaluated for its polysaccharide content, scanning electron microscopy (SEM) imaging, acid-producing ability, and related lactic dehydrogenase (LDH), arginine deiminase (ADS), and urease enzymatic activity determination. Fluorescence in situ hybridization (FISH) and quantitative real-time polymerase chain reaction (qRT-PCR) were used to evaluate the S. mutans ratio within the biofilm. It was followed by 16S rRNA sequencing to define the oral microbial community.ResultsFluoride-resistant S. mutans produced increased polysaccharides in presence of NaF (P &lt; 0.05). The enzymatic activities related to both acid and base generation were less affected by the fluoride. In presence of 275 ppm NaF, the pH in the fluoride-resistant strain sample was lower than the wild type. We observed that with the biofilm development and accumulative fluoride concentration, the fluoride-resistant strain had positive relationships with other bacteria within the oral microbial community, which enhanced its colonization and survival. Compared to the wild type, fluoride-resistant strain significantly increased the diversity and difference of oral microbial community at the initial stage of biofilm formation (4 and 24 h) and at a low fluoride environment (0 and 275 ppm NaF) (P &lt; 0.05). Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that fluoride-resistant strain enhanced the metabolic pathways and glucose transfer.ConclusionsFluoride-resistant S. mutans affected the microecological balance of oral biofilm and its cariogenic properties in vitro, indicating its negative impact on fluoride's caries prevention effect.