Antibacterial and antibiofilm activities of novel antimicrobial peptide DP7 against the periodontal pathogen Porphyromonas gingivalis

Aims Accumulating evidence suggests that Porphyromonas gingivalis is closely associated with the development of various chronic inflammatory diseases, particularly periodontitis. This study investigated the antibacterial activity and action mechanism of a novel antimicrobial peptide (AMP), DP7, against P. gingivalis. Methods and Results The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for DP7 were determined via a broth microdilution method, revealing an MIC of 8 μg ml−1 and MBC of 32 μg ml−1. Growth inhibition and killing assays confirmed the bactericidal effect of DP7, and treatment with DP7 at MBC eliminated P. gingivalis within 8 h. DP7 had a low cytotoxic effect against human cells. Transmission electron microscopy revealed that DP7 destroyed the bacterial membrane, and confocal laser scanning microscopy revealed its inhibitory effect on P. gingivalis biofilms. Quantitative reverse transcription‐polymerase chain reaction revealed DP7‐mediated inhibition of several virulence factor genes, partially explaining its antibacterial mechanism. Conclusions DP7, a novel AMP with low mammalian cytotoxicity, inhibits both planktonic and biofilm forms of P. gingivalis by destroying the bacterial membrane and reducing virulence factor gene expression. Significance and Impact of the Study DP7 has potential clinical application in the prevention and treatment of P. gingivalis‐associated diseases.