Antibacterial effects and microarray-based molecular mechanisms of -cinnamaldehyde against .

() is one of the keystone pathogenic bacteria of periodontitis and peri-implantitis. This study aimed to investigate the antibacterial effects and molecular mechanisms of -cinnamaldehyde (TC), a safe extract from natural plants, on . Minimum inhibitory and minimum bactericidal concentrations (MIC and MBC) of TC were determined, and scanning and transmission electron microscopies were used to assess the morphological changes. The overall biomass was estimated, and the metabolic activity of biofilms was determined at different TC concentrations. A microarray-based bioinformatics analysis was performed to elucidate the underlying molecular mechanisms of TC-inhibited , and significant differences among groups were determined. TC showed an inhibitory effect on the proliferation and survival of planktonic , of which the MIC and MBC were 39.07 μg/mL and 78.13 μg/mL, respectively. TC also significantly suppressed the formation and metabolic activity of biofilm. The results of the significant pathways and gene ontology (GO) analyses revealed that TC treatment inhibited two metabolic pathways, accompanied by the downregulation of relative genes of nitrogen metabolism (, , and ) and starch and sucrose metabolism (, , and ). Thus, this study confirmed TC to be a natural antimicrobial agent against and further demonstrated that TC suppressed the microbial activity on through the disruption of physiological metabolism, which might inhibit the growth and the biofilm formation of .