Periodontal pathogens produce quorum sensing signal molecules

Different species of bacteria important in the composition of dental plaque were tested for production of extracellular autoinducer like activities th at stimulate the expression of the luminescence genes in Vibrio harveyi. Se veral strains of Prevotella intermedia, Fusobacterium nucleatum, and Porphy romonas gingivalis were found to produce such activities. Interestingly, th ese bacteria belong to the same phylogenetic group, and they are periodonta l pathogens important in the development of periodontal disease. They speci fically produce extracellular signaling molecule related autoinducer-2 from V.haveyi. Nevertheless, they seem to be unable to produce homologues of ac yl-homoserine lactones. Furthermore, Escherichia coli DH5 alpha can be comp lemented by the introduction of a P, gingivalis gene with high homology to the luxS gene, which has been called luxS(P.g.*).