Comparative gene expression analysis of planktonic Porphyromonas gingivalis ATCC 33277 in the presence of a growing biofilm versus planktonic cells

BACKGROUND: Porphyromonas gingivalis, a microorganism residing in the oral cavity within complex multispecies biofilms, is one of the keystone pathogens in the onset and progression of periodontitis. In this in vitro study, using DNA microarray, we investigate the differential gene expression of Porphyromonas gingivalis ATCC 33277 when growing in the presence or in absence of its own monospecies biofilm. RESULTS: Approximately 1.5% of genes (28 out of 1909 genes, at 1.5 fold change or more, p-value < 0.05) were differentially expressed by P. gingivalis cells when in the presence of a biofilm. These genes were predominantly related to the metabolism of iron, bacterial adhesion, invasion, virulence and quorum-sensing system. The results from microarrays were consistent with those obtained by RT-qPCR. CONCLUSION: This study provides insight on the transcriptional changes of planktonic P. gingivalis cells when growing in the presence of a biofilm. The resulting phenotypes provide information on changes occurring in the gene expression of this pathogen.