Abstract
Objective:To investigate the relation between biofilm formation ability and quorum sensing gene LuxS/AI-2.Materials and Methods: Enterococcus faecalis (E. faecalis) standard strain ATCC 29212 was used in the study. Long flanking homology polymerase chain reaction method was used to build the LuxS gene knockout strain. Sequential culture turbidity measurement and CFU counting were used to assess the proliferation ability of E. faecalis after the depletion of LuxS. 96-well plate assay was used to quantify the biofilm formation ability; CLSM was used to observe the attached bacteria areas, while scanning electron microscopy (SEM) was performed to observe biofilm microstructure conditions.Results:LuxS gene knockout strains were successfully constructed and identified. The results showed that proliferation ability of E. faecalis was not affected by the depletion of the luxS gene, and the biofilm formation ability of ΔLuxS 29212 significantly decreased (P<0.05).Conclusions:Collectively, our studies provide the LuxS gene's key role in controlling biofilm formation of E. faecalis, which presented a negative regulation, and furthermore, providing us a possible way to conquer the persistent apical periodontitis.
Highlights
10-20% of teeth are not healed by apical lesions after re-treatment in endodontic therapy; this condition is called persistent apical periodontitis (PAP)
Biofilm formation is considered as the primary pathogenic factor resulting in persistent infections and treatment failures, while Enterococcus faecalis (E. faecalis) has been reported to be a highly detected pathogenic bacteria from the extraradicular biofilm and is one of the highly investigated bacteria associated with PAP lesions10-13
The gene knockout enabled to test the specific function of the LuxS gene and observe the biofilm formation change regulated by quorum sensing system
Summary
10-20% of teeth are not healed by apical lesions after re-treatment in endodontic therapy; this condition is called persistent apical periodontitis (PAP). Bacterial infection was recognized as the dominant cause of PAP1. A number of investigations have shown that most root canal treatment failures are caused by microorganisms surviving around the apical foramen by forming a biofilm structure, invading the extraradicular area, and attaching to the cementum around the root apex. The eradication of apical microorganisms by endodontic microsurgery resulted in a successful outcome based on a variety of follow-up studies. Biofilm formation is considered as the primary pathogenic factor resulting in persistent infections and treatment failures, while Enterococcus faecalis (E. faecalis) has been reported to be a highly detected pathogenic bacteria from the extraradicular biofilm and is one of the highly investigated bacteria associated with PAP lesions. The mechanism of the E. faecalis biofilm formation remains elusive
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