Abstract
BackgroundBiofilm formation in E. faecalis is presumed to play an important role in a number of enterococcal infections. We have previously identified a genetic locus provisionally named bop that is involved in maltose metabolism and biofilm formation. A transposon insertion into the second gene of the locus (bopB) resulted in loss of biofilm formation, while the non-polar deletion of this gene, together with parts of the flanking genes (bopA and bopC) resulted in increased biofilm formation. A polar effect of the transposon insertion on a transcriptional regulator (bopD) was responsible for the reduced biofilm formation of the transposon mutant.ResultsThe amount of biofilm formed is related to the presence of maltose or glucose in the growth medium. While the wild-type strain was able to produce biofilm in medium containing either glucose or maltose, two mutants of this locus showed opposite effects. When grown in medium containing 1% glucose, the transposon mutant showed reduced biofilm formation (9%), while the deletion mutant produced more biofilm (110%) than the wild-type. When grown in medium containing 1% maltose, the transposon mutant was able to produce more biofilm than the wild-type strain (111%), while the deletion mutant did not produce biofilm (4%). Biofilm formation was not affected by the presence of several other sugar sources. In a gastrointestinal colonization model, the biofilm-negative mutant was delayed in colonization of the mouse intestinal tract.ConclusionThe biofilm-positive phenotype of the wild-type strain seems to be associated with colonization of enterococci in the gut and the presence of oligosaccharides in food may influence biofilm formation and therefore colonization of enterococci in the gastrointestinal system.
Highlights
Biofilm formation in E. faecalis is presumed to play an important role in a number of enterococcal infections
The transposon insertion occurred into the second gene of the operon, but the reduction of biofilm formation is related to a polar effect on the 4. gene
Since bopD exhibits significant sequence homology with a number of bacterial proteins involved in the regulation of maltose metabolism [10], we evaluated the biofilm formation in medium containing glucose or maltose of the wild-type (E. faecalis T9) and two mutants, a biofilm-negative transposon mutant (E. faecalis 10D5 with insertion of the transposon into the bopB gene) and a biofilm-enhanced deletion mutant (E. faecalis TDM with deletions of parts of bopA and bopC and all of bopB)
Summary
Biofilm formation in E. faecalis is presumed to play an important role in a number of enterococcal infections. We have previously identified a genetic locus provisionally named bop that is involved in maltose metabolism and biofilm formation. A polar effect of the transposon insertion on a transcriptional regulator (bopD) was responsible for the reduced biofilm formation of the transposon mutant. The transposon insertion occurred into the second gene of the operon, but the reduction of biofilm formation is related to a polar effect on the 4. Since bopD exhibits significant sequence homology with a number of bacterial proteins involved in the regulation of maltose metabolism [10], we evaluated the biofilm formation in medium containing glucose or maltose of the wild-type (E. faecalis T9) and two mutants, a biofilm-negative transposon mutant (E. faecalis 10D5 with insertion of the transposon into the bopB gene) and a biofilm-enhanced deletion mutant (E. faecalis TDM with deletions of parts of bopA and bopC and all of bopB). The possibile effect of oligosaccharide in the diet on the colonization and biofilm production of resident enterococci in mice was evaluated
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