Department of Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany.
Appl Environ Microbiol. 2012 Sep;78(17):6217-24. doi: 10.1128/AEM.01525-12. Epub 2012 Jun 29.
Among the adaptive responses of bacteria to rapid changes in environmental conditions, those of the cell envelope are known to be the most crucial. Therefore, several mechanisms with which bacteria change their cell surface and membranes in the presence of different environmental stresses have been elucidated. Among these mechanisms, the release of outer membrane vesicles (MV) in Gram-negative bacteria has attracted particular research interest because of its involvement in pathogenic processes, such as that of Pseudomonas aeruginosa biofilm formation in cystic fibrosis lungs. In this study, we investigated the role of MV formation as an adaptive response of Pseudomonas putida DOT-T1E to several environmental stress factors and correlated it to the formation of biofilms. In the presence of toxic concentrations of long-chain alcohols, under osmotic stress caused by NaCl, in the presence of EDTA, and after heat shock, cells of this strain released MV within 10 min in the presence of a stressor. The MV formed showed similar size and charge properties, as well as comparable compositions of proteins and fatty acids. MV release caused a significant increase in cell surface hydrophobicity, and an enhanced tendency to form biofilms was demonstrated in this study. Therefore, the release of MV as a stress response could be put in a physiological context.
在细菌对环境条件快速变化的适应反应中，已知细胞包膜的适应反应最为关键。因此，已经阐明了几种细菌在存在不同环境压力时改变其细胞表面和膜的机制。在这些机制中，革兰氏阴性菌中外膜囊泡（MV）的释放因其参与致病性过程而引起了特别的研究兴趣，例如铜绿假单胞菌在囊性纤维化肺中的生物膜形成。在这项研究中，我们研究了 MV 形成作为假单胞菌 DOT-T1E 对几种环境应激因子的适应反应的作用，并将其与生物膜的形成相关联。在存在长链醇的毒性浓度下，在由 NaCl 引起的渗透压应激下，在存在 EDTA 的情况下，以及在热冲击后，该菌株的细胞在应激物存在的情况下在 10 分钟内释放 MV。形成的 MV 表现出相似的大小和电荷特性，以及类似的蛋白质和脂肪酸组成。在这项研究中，MV 释放导致细胞表面疏水性显著增加，并证明了形成生物膜的趋势增强。因此，MV 的释放作为应激反应可以被置于生理环境中。
