Ayrapetyan Mesrop, Williams Tiffany C, Oliver James D
Department of Biology, The University of North Carolina at Charlotte, Charlotte, North Carolina, USA.
Appl Environ Microbiol. 2014 Apr;80(8):2478-83. doi: 10.1128/AEM.00080-14. Epub 2014 Feb 7.
Entry and exit from dormancy are essential survival mechanisms utilized by microorganisms to cope with harsh environments. Many bacteria, including the opportunistic human pathogen Vibrio vulnificus, enter a form of dormancy known as the viable but nonculturable (VBNC) state. VBNC cells can resuscitate when suitable conditions arise, yet the molecular mechanisms facilitating resuscitation in most bacteria are not well understood. We discovered that bacterial cell-free supernatants (CFS) can awaken preexisting dormant vibrio populations within oysters and seawater, while CFS from a quorum sensing mutant was unable to produce the same resuscitative effect. Furthermore, the quorum sensing autoinducer AI-2 could induce resuscitation of VBNC V. vulnificus in vitro, and VBNC cells of a mutant unable to produce AI-2 were unable to resuscitate unless the cultures were supplemented with exogenous AI-2. The quorum sensing inhibitor cinnamaldehyde delayed the resuscitation of wild-type VBNC cells, confirming the importance of quorum sensing in resuscitation. By monitoring AI-2 production by VBNC cultures over time, we found quorum sensing signaling to be critical for the natural resuscitation process. This study provides new insights into the molecular mechanisms stimulating VBNC cell exit from dormancy, which has significant implications for microbial ecology and public health.
进入和脱离休眠是微生物用来应对恶劣环境的重要生存机制。许多细菌，包括机会性人类病原体创伤弧菌，会进入一种被称为活的但不可培养（VBNC）状态的休眠形式。当合适的条件出现时，VBNC细胞可以复苏，但大多数细菌中促进复苏的分子机制尚未得到很好的理解。我们发现细菌无细胞上清液（CFS）可以唤醒牡蛎和海水中预先存在的休眠弧菌种群，而群体感应突变体的CFS则无法产生相同的复苏效果。此外，群体感应自诱导物AI-2可以在体外诱导VBNC创伤弧菌的复苏，并且无法产生AI-2的突变体的VBNC细胞无法复苏，除非培养物中添加外源性AI-2。群体感应抑制剂肉桂醛延迟了野生型VBNC细胞的复苏，证实了群体感应在复苏中的重要性。通过监测VBNC培养物随时间的AI-2产生情况，我们发现群体感应信号对于自然复苏过程至关重要。这项研究为刺激VBNC细胞脱离休眠的分子机制提供了新的见解，这对微生物生态学和公共卫生具有重要意义。
