Evans M, Davies J K, Sundqvist G, Figdor D
School of Dental Science, University of Melbourne, Australia.
Int Endod J. 2002 Mar;35(3):221-8. doi: 10.1046/j.1365-2591.2002.00504.x.
This study sought to clarify the mechanisms that enable E. faecalis to survive the high pH of calcium hydroxide.
E. faecalis strain JH2-2 was exposed to sublethal concentrations of calcium hydroxide, with and without various pretreatments. Blocking agents were added to determine the role of stress-induced protein synthesis and the cell wall-associated proton pump.
E. faecalis was resistant to calcium hydroxide at a pH of 11.1, but not pH 11.5. Pre-treatment with calcium hydroxide pH 10.3 induced no tolerance to further exposure at pH 11.5. No difference in cell survival was observed when protein synthesis was blocked during stress induction, however, addition of a proton pump inhibitor resulted in a dramatic reduction of cell viability of E. faecalis in calcium hydroxide.
Survival of E. faecalis in calcium hydroxide appears to be unrelated to stress induced protein synthesis, but a functioning proton pump is critical for survival of E. faecalis at high pH.
本研究旨在阐明粪肠球菌在氢氧化钙高pH环境中存活的机制。
将粪肠球菌菌株JH2-2暴露于亚致死浓度的氢氧化钙中，进行和不进行各种预处理。添加阻断剂以确定应激诱导的蛋白质合成和细胞壁相关质子泵的作用。
粪肠球菌在pH为11.1的氢氧化钙环境中具有抗性，但在pH为11.5时不具有抗性。用pH为10.3的氢氧化钙预处理不会诱导对pH为11.5的进一步暴露产生耐受性。在应激诱导期间阻断蛋白质合成时，未观察到细胞存活率的差异，然而，添加质子泵抑制剂会导致粪肠球菌在氢氧化钙中的细胞活力显著降低。
粪肠球菌在氢氧化钙中的存活似乎与应激诱导的蛋白质合成无关，但正常运作的质子泵对于粪肠球菌在高pH环境中的存活至关重要。
