2014) and subsequent nutrient limited environment (Sundqvist et al. faecalis is one of the most commonly recovered bacteria from persistent root canal infections, suggesting that it has the capacity to survive the chemomechanical procedures (Yap et al. faecalis reported to fall to 0.001% at pH 11 and 0.00001% at pH 12 (Appelbe and Sedgley 2007). Calcium hydroxide kills bacteria by direct contact through pH effects and is known to dramatically reduce the bacterial load in root canals with survival of E. Endodontic treatment (root canal therapy) of a tooth with a necrotic pulp usually involves the chemo-mechanical debridement of the canal(s) with irrigants such as sodium hypochlorite and often interappointment medicaments such as calcium hydroxide (∼ pH 12.5–12.8) placed in the main root canal to help in the elimination of surviving bacteria (Siqueira and Lopes 1999). faecalis seem to be involved in a shift of carbohydrate metabolism from the PTS system to glycerol, which supports the formation of a protective capsule protecting the cell.Īlkaline pH, biofilm, continuous culture, Enterococcus faecalis, ICPL, membrane shaving IntroductionĮnterococcus faecalis is commonly recovered from food, the oral cavity, and clinical specimens (Anderson et al. In extreme alkaline conditions, the membrane proteins of E. A total of five proteins were down-regulated including: EF0108 (C4-dicarboxylate transporter) EF1838 (PTS system IIC component) EF0456 (PTS system IID component) and EF0022 (PTS mannose-specific IID component). A total of six proteins were up-regulated in pH 11 including: EF0669 (polysaccharide biosynthesis family) EF1927 (glycerol uptake facilitator), and EF0114 (glycosyl hydrolase). Ratios of membrane proteins were log 2 transformed, with proteins deviating by more than 1 SD of the mean considered to be up- or down-regulated. The relative proportion of membrane proteins were identified using LC-ESI mass spectrometry and MaxQuant analysis. Following membrane shaving, isotope-coding protein labels were added at the peptide level to samples and then combined. faecalis V583 in a chemostat at pH 8 and 11 at one-tenth the organism’s relative maximum growth rate. faecalis membrane proteins play in survival strategies to extreme alkaline conditions is unclear. Enterococcus faecalis is able to adapt to alkaline conditions and is commonly recovered from teeth in which endodontic treatment has failed.
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