Impact of Quorum Sensing Inhibitors on Population Dynamics of Oral Bacteria

Quorum sensing (QS) signaling system of bacteria play a crucial role in controlling their population densities and interactions with each other as well as with their environments. The human oral cavity harbors one of the most complex microbiota of which one third of the species are yet cultivated. Isolation and culturing of oral bacteria is critical to understand their impact on health and diseases. In this study, we investigated the effect of QS inhibitors on the cultivability of oral bacteria and their population density by disrupting their QS signals. Oral samples were collected from six healthy individuals and seeded on agar media in the presence of QS inhibitors. Based on colony morphology and Gram staining, 121 colonies grown only on the agar media containing QS inhibitors, but not on the control agar media without QS inhibitors, were picked and characterized using standard bacteriological methods. Of the 121 isolates, 26 strains were further characterized by 16S rRNA sequence analysis, and a phylogenetic tree was constructed. These 26 strains belonged to the phyla of Actinobacteria, Firmicutes, and Proteobacteria. The results of this study indicated that culturing oral bacteria in the presence of QS inhibitors may alter their population densities which in turn promote cultivation and identification of bacteria that may be suppressed in various environments including different parts of the human body. Keywords: 16S ribosomal RNA, oral cavity, population density, quorum sensing DOI: 10.7176/JBAH/9-18-03 Publication date:September 30th 201