Anti-biofilm and antivirulence activities of 1,2,6-tri-O-galloyl-β-d-glucose against Proteus penneri

Abstract

Abstract Aims The present study investigated the anti-virulence and anti-biofilm effects of 1,2,6-tri-O-galloyl-β-d-glucose (TGG), isolated from Camellia nitidissima Chi flowers, on Proteus penneri ALK 1200. Methods and results TGG was isolated from C. nitidissima Chi flowers using various chromatographic techniques. The milk plate assay, azocasein assay, and exopolysaccharides (EPS) inhibition assay revealed that TGG effectively inhibited the production of crucial virulence factors, including protease and EPS, in P. penneri ALK 1200. Furthermore, Fourier transform infrared spectroscopic analysis indicated that TGG interfered with the composition of P. penneri ALK 1200’s cellular component, potentially reducing the bacteria’s pathogenicity. In addition, crystal violet assay, scanning electron microscopy, and confocal laser scanning microscopy analysis indicated a significant reduction in biofilm formation following TGG treatment. The swimming and swarming assays also showed that TGG reduced the motility of P. penneri ALK 1200. Furthermore, the quantitative real-time PCR assay demonstrated that TGG down-regulated the expression of positive regulatory genes (hfq and flhD) responsible for motility and biofilm formation, while up-regulating the expression of the negative regulator of the quorum sensing system, bssS, in P. penneri ALK 1200. Conclusions TGG displayed potent anti-QS and anti-biofilm activity toward P. penneri ALK 1200.