Sub-lethal stress effects on virulence gene expression in Enterococcus faecalis
Sub-lethal stress effects on virulence gene expression in Enterococcus faecalis
复制标题
DOI：
10.1016/j.fm.2009.11.008
复制
发表时间：
2010-05-01
影响因子：
5.3
通讯作者：
Vogel, Rudi F.
中科院分区：
文献类型：
--
作者：
Lenz, Christian A.;Ferstl, Carrie M. Hew;Vogel, Rudi F.
肠球菌是一种广泛存在于人体消化道的乳酸菌。此外，这些微生物在食品中具有长期的使用历史，可以改善风味，并作为益生菌或抗菌添加剂提供保护机制。然而，粪肠球菌占血液、伤口、泌尿道和心脏的所有医院感染的高达10%。关于毒力因子调控的知识是有限的，环境信号的参与有助于E。粪菌致病性的记录很少。在本研究中，两个临床E。将粪肠球菌分离株TMW 2.63和OG1RF以及一种食物分离株TMW 2.629分别经受六种亚致死食物和宿主相关应激，包括6.8%NaCl、200 ppm亚硝酸盐、51 ℃、80 MPa、pH 4.1和0.08%胆汁盐（胆酸：鹅去氧胆酸1：1），将它们的生长速率降低至10%。通过使用真实的时间PCR和Lightcycler（R）技术（参考条件：BHI肉汤）定量15个胁迫和毒力相关基因的相对基因表达，所述15个胁迫和毒力相关基因包括dnaK、groEL、ctsR、clpPBCEX、gls24、efaAfs、ace、fsrB、gelE、sprE和cylB。37 ℃，pH = 7.4）。除了菌株依赖性差异外，亚致死环境胁迫能够引起大肠杆菌中毒力相关基因表达的显著改变。粪便菌从临床以及食物来源的分离。这些结果有助于在食品生产过程中避免预处理肠球菌，并了解在E。粪便菌转变为致病菌(C)2009爱思唯尔有限公司保留所有权利。
Enterococci are ubiquitous lactic acid bacteria commonly associated with the human digestive tract as commensal organisms. Additionally, these organisms have a long history of use in foods improving flavor as well as providing protective mechanisms as either a probiotic or antimicrobial additive. However, Enterococcus faecalis accounts for up to 10% of all nosocomial infections of the bloodstream, wounds, urinary tract and heart. Knowledge about the regulation of virulence factors is limited and the involvement of environmental signals contributing to E. faecalis pathogenicity is poorly documented. In this study, two clinical E. faecalis isolates, TMW 2.63 and OG1RF, as well as one food isolate, TMW 2.629, were subjected to six sub-lethal food- and host-related stresses including 6.8% NaCl, 200 ppm nitrite, 51 degrees C, 80 MPa, pH 4.1 and 0.08% bile salts (cholic acid:chenodeoxycholic acid 1:1), respectively, reducing their growth rate to 10%. Relative gene expression of 15 stress and virulence-associated genes including dnaK, groEL, ctsR, clpPBCEX, gls24, efaAfs, ace, fsrB, gelE, sprE and cylB, was quantified by using real time PCR and Lightcycler (R) technology (reference conditions: BHI broth. 37 degrees C, pH = 7.4). Apart from strain-dependent differences, sub-lethal environmental stress was capable of provoking significant alterations in the expression of virulence-associated genes in E. faecalis from clinical as well as food origins of isolation. These results help to avoid preconditioning enterococci in food production processes and to understand the complex mechanisms in E. faecalis' switch to pathogenicity. (C) 2009 Elsevier Ltd. All rights reserved.