Proteomic and Transcriptional Analysis of Interaction between Oral Microbiota Porphyromonas gingivalis and Streptococcus oralis

Porphyromonas gingivalis, a major
periodontal pathogen, forms biofilm with other oral bacteria such
as streptococci. Here, by using shotgun proteomics, we examined the
molecular basis of mixed-biofilm formation by P. gingivalis with Streptococcus oralis. We identified
a total of 593 bacterial proteins in the biofilm. Compared to the
expression profile in the P. gingivalis monobiofilm, the expression of three proteins was induced and that
of 31 proteins was suppressed in the mixed biofilm. Additionally,
the expression of two S. oralis proteins
was increased, while that of two proteins was decreased in the mixed
biofilm, as compared to its monotypic profile. mRNA expression analysis
of selected genes using a quantitative reverse transcription polymerase
chain reaction confirmed the proteomics data, which included overexpression
of P. gingivalis FimA and S. oralis glyceraldehyde-3-phosphate dehydrogenase
in association with the biofilm. The results also indicated that S. oralis regulates the transcriptional activity
of P. gingivalis luxS to influence autoinducer-2-dependent signaling. These findings suggest
that several functional molecules are involved in biofilm formation
between P. gingivalis and S. oralis.