Burt Sara A, van der Zee Ruurd, Koets Ad P, de Graaff Anko M, van Knapen Frans, Gaastra Wim, Haagsman Henk P, Veldhuizen Edwin J A
Institute for Risk Assessment Sciences, Division of Veterinary Public Health, Faculty of Veterinary Medicine, Utrecht University, 3508TD Utrecht, The Netherlands.
Appl Environ Microbiol. 2007 Jul;73(14):4484-90. doi: 10.1128/AEM.00340-07. Epub 2007 May 25.
The essential oils of oregano and thyme are active against a number of food-borne pathogens, such as Escherichia coli O157:H7. Carvacrol is one of the major antibacterial components of these oils, and p-cymene is thought to be its precursor in the plant. The effects of carvacrol and p-cymene on protein synthesis in E. coli O157:H7 ATCC 43895 cells were investigated. Bacteria were grown overnight in Mueller-Hinton broth with a sublethal concentration of carvacrol or p-cymene, and their protein compositions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and confirmed by Western blotting. The presence of 1 mM carvacrol during overnight incubation caused E. coli O157:H7 to produce significant amounts of heat shock protein 60 (HSP60) (GroEL) (P < 0.05) and inhibited the synthesis of flagellin highly significantly (P < 0.001), causing cells to be aflagellate and therefore nonmotile. The amounts of HSP70 (DnaK) were not significantly affected. p-Cymene at 1 mM or 10 mM did not induce HSP60 or HSP70 in significant amounts and did not have a significant effect on flagellar synthesis. Neither carvacrol (0.3, 0.5, 0.8, or 1 mM) nor p-cymene (0.3, 0.5, or 0.8 mM) treatment of cells in the mid-exponential growth phase induced significant amounts of HSP60 or HSP70 within 3 h, although numerical increases of HSP60 were observed. Motility decreased with increasing concentrations of both compounds, but existing flagella were not shed. This study is the first to demonstrate that essential oil components induce HSP60 in bacteria and that overnight incubation with carvacrol prevents the development of flagella in E. coli O157:H7.
牛至和百里香的精油对多种食源性病原体具有活性，如大肠杆菌O157:H7。香芹酚是这些精油的主要抗菌成分之一，对伞花烃被认为是其在植物中的前体。研究了香芹酚和对伞花烃对大肠杆菌O157:H7 ATCC 43895细胞蛋白质合成的影响。细菌在含有亚致死浓度香芹酚或对伞花烃的 Mueller-Hinton 肉汤中过夜培养，通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳分析其蛋白质组成，并通过蛋白质印迹法进行确认。过夜培养期间存在1 mM香芹酚会导致大肠杆菌O157:H7产生大量热休克蛋白60（HSP60）（GroEL）（P < 0.05），并高度显著抑制鞭毛蛋白的合成（P < 0.001），使细胞无鞭毛，因此无运动能力。HSP70（DnaK）的量没有受到显著影响。1 mM或10 mM的对伞花烃不会大量诱导HSP60或HSP70，并且对鞭毛合成没有显著影响。在指数生长中期用香芹酚（0.3、0.5、0.8或1 mM）或对伞花烃（0.3、0.5或0.8 mM）处理细胞3小时内，均未大量诱导HSP60或HSP70，尽管观察到HSP60有数值上的增加。运动能力随着两种化合物浓度的增加而降低，但现有鞭毛不会脱落。本研究首次证明精油成分可在细菌中诱导HSP60，并且与香芹酚过夜培养可阻止大肠杆菌O157:H7鞭毛的形成。
