Strains of Enterococcus faecalis differ in their ability to coexist in biofilms with other root canal bacteria

• AimTo investigate the relationship between protease production and the ability of Enterococcus faecalis strains to coexist in biofilms with other bacteria commonly recovered from infected root canals. MethodologyBiofilms with bacteria in mono-, dual- and four-species communities were developed in flow chambers. The organisms used were Lactobacillus salivarius, Streptococcus gordonii and Actinomyces naeslundii and E.faecalis strains, GUL1 and OG1RF. Biovolume and species distribution were examined using 16S rRNA fluorescence insitu hybridization in combination with confocal microscopy and image analysis. The full proteome of the E.faecalis strains was studied using two-dimensional gel electrophoresis. Spots of interest were identified using tandem mass spectroscopy and quantified using Delta 2D software. ResultsAll bacteria formed biofilms and an anova analysis revealed that the biofilm biomass increased significantly (P0.01) between 6 and 24h. L.salivarius, S.gordonii and A.naeslundii formed mutualistic biofilm communities, and this pattern was unchanged when E.faecalis GUL1 was included in the consortium. However, with OG1RF, L.salivarius and S.gordonii were outcompeted in a 24-h biofilm. Proteomic analysis revealed that OG1RF secreted higher levels of proteases, GelE (P=0.02) and SprE (P=0.002) and a previously unidentified serine protease (P=0.05), than GUL1. ConclusionsDifferent strains of E.faecalis can interact synergistically or antagonistically with a consortium of root canal bacteria. A possible mechanism underlying this, as well as potential differences in virulence, is production of different levels of proteases, which can cause detachment of neighbouring bacteria and tissue damage.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Odontologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Dentistry (hsv//eng)

Keyword

antagonism

apical periodontitis

bacterial consortium

multispecies

mutualism

apical periodontitis

endodontic infections

teeth

identification

susceptibility

pathogenicity

community

serum

dna

Dentistry

Oral Surgery & Medicine

mixed species biofilm

Publication and Content Type

ref (subject category)

art (subject category)