Sessile growth on human dentine is associated with ace gene expression in Enterococcus faecalis: An ex vivo study

Background: Evidence regarding the role of the ace gene in biofilms generally stems from DNA detection studies conducted under planktonic conditions, rather than from models that have assessed the functional expression of the gene. Aim: To determine whether sessile growth in a biofilm on human dentine in an ex vivo model modifies the expression of the ace gene in Enterococcus faecalis clinical strains. Materials and Methods: Seventy biofilm-forming clinical isolates were cultured in planktonic and sessile states using an ex vivo human dentine model. Their ability to form biofilm on dentine was assessed by electron microscopy. After total RNA extraction from both bacterial growth states, ace gene expression was confirmed by reverse transcriptase–polymerase chain reaction (RT-PCR). Paired differences were analyzed using the exact McNemar test. Results: Detectable ace gene expression was observed more frequently in the sessile condition (85.7%) than in the planktonic condition (75.7%), with a statistically significant difference ( P = 0.023). Seven isolates expressed the ace gene upon transitioning from a planktonic to a sessile state. Conclusion: Sessile biofilms showed more frequently detectable ace gene expression than in the planktonic state.