Department of Microbiology, Soochow University, Taipei, Taiwan 111, Republic of China.
Int J Food Microbiol. 2010 Jun 15;140(2-3):232-8. doi: 10.1016/j.ijfoodmicro.2010.03.027. Epub 2010 Mar 27.
Vibrio vulnificus is an opportunistic pathogen commonly found in oyster and marine environments, which frequently encounters different stresses in its natural habitat, food processing environment and during infection. In this paper, the adaptation of V. vulnificus to bile and the role of RpoS in this process were examined using a wild-type strain and an rpoS isogenic mutant. Adaptation to bile was readily induced in the exponential phase cells in phosphate-buffered saline with 2% bile salts, and the adapted cells exhibited enhanced tolerance against 10% bile. Addition of 1% Brain Heart Infusion medium to the adaptation medium significantly increased the survival of V. vulnificus against bile. The bile-adapted cells were cross-protected against alkaline treatment but sensitized against acid, heat, high salinity and detergents (sodium dodecyl sulfate, Triton X-100, 3-[(3-cholamidopropyl) dimethylammonio]- 1- propanesulfonate, and cetylpyridinium bromide). Addition of efflux pump inhibitor (carbonyl cyanide m-chlorophenylhydrazone) or protein synthesis inhibitor (chloramphenicol) completely eliminated or down-graded the enhanced bile tolerance of the adapted cells, respectively. Production of GroEL was not markedly influenced but DnaK was inhibited in the bile-adapted cells. The bile-adapted parent strain exhibited significantly higher survival than the rpoS mutant against the challenge of high pH, heat, high salinity and detergents. The induction of bile-adaptation in the rpoS mutant occurred at a significantly slower rate than for the parent strain. Results indicate that RpoS plays a significant role in the response of V. vulnificus to bile.
创伤弧菌是一种机会致病菌，通常存在于牡蛎和海洋环境中，在其自然栖息地、食品加工环境和感染过程中经常会遇到不同的压力。在本文中，使用野生型菌株和 rpoS 同源突变株研究了创伤弧菌对胆盐的适应及其在该过程中的作用。在磷酸盐缓冲盐水（含 2%胆盐）中的指数生长期细胞中，很容易诱导对胆盐的适应，适应后的细胞对 10%胆盐的耐受性增强。在适应培养基中添加 1%脑心浸液可显著提高创伤弧菌对胆盐的存活率。经胆盐适应的细胞对碱性处理具有交叉保护作用，但对酸、热、高盐度和去污剂（十二烷基硫酸钠、Triton X-100、3-[(3-胆酰胺丙基)二甲基氨基]-1-丙磺酸钠和十六烷基吡啶溴化物）敏感。添加外排泵抑制剂（羰基氰化物 m-氯苯腙）或蛋白质合成抑制剂（氯霉素）可分别完全消除或降低适应细胞对胆盐的增强耐受性。GroEL 的产生没有明显受到影响，但在适应胆盐的细胞中 DnaK 被抑制。适应胆盐的亲本菌株在高 pH 值、热、高盐度和去污剂的挑战下比 rpoS 突变体具有更高的存活率。rpoS 突变体中胆盐适应的诱导速度明显慢于亲本菌株。结果表明，RpoS 在创伤弧菌对胆盐的反应中起重要作用。
