Center for Proteomics, State Key Laboratory of Bio-Control, School of Life Sciences, Guangdong Province Key Laboratory for Pharmaceutical Functional Genes, Sun Yat-sen University, University City, Guangzhou, 510006, People's Republic of China.
Environ Microbiol. 2018 Nov;20(11):4022-4036. doi: 10.1111/1462-2920.14443. Epub 2018 Oct 30.
The development of antibiotic resistance in Vibrio alginolyticus represents a threat to human health and fish farming. Environmental NaCl regulation of bacterial physiology is well documented, but whether the regulation contributes to antibiotic resistance remains unknown. To explore this, we compared minimum inhibitory concentration (MIC) of V. alginolyticus cultured in different media with 0.5%-10% NaCl, and found that the MIC increased as the NaCl concentration increased, especially for aminoglycoside antibiotics. Consistent with this finding, internal NaCl also increased, while intracellular gentamicin level decreased. GC-MS-based metabolomics showed different distributions of pyruvate cycle intermediates among 0.5%, 4% and 10% NaCl. Differential activity of enzymes in the pyruvate cycle and altered expression of Na(+)-NQR led to a reducing redox state, characterized by decreased levels of NADH, proton motive force (PMF) and ATP. Meanwhile, NaCl negatively regulated PMF as a consequence of the reducing redox state. These together are responsible for the decreased intracellular gentamicin level with the increased external level of NaCl. Our study reveals a previously unknown redox state-dependent mechanism regulated by NaCl in V. alginolyticus that impacts antibiotic resistance.
在弧菌属中抗生素耐药性的发展对人类健康和水产养殖构成了威胁。环境中氯化钠对细菌生理的调节已有大量文献记载，但这种调节是否有助于抗生素耐药性尚不清楚。为了探讨这一问题，我们比较了在 0.5%至 10%氯化钠浓度的不同培养基中培养的弧菌属最小抑菌浓度（MIC），结果发现 MIC 随着氯化钠浓度的升高而升高，特别是氨基糖苷类抗生素。这一发现与内部氯化钠的增加以及细胞内庆大霉素水平的降低相一致。基于 GC-MS 的代谢组学研究显示，在 0.5%、4%和 10%氯化钠中，丙酮酸循环中间产物的分布不同。丙酮酸循环中酶的不同活性和 Na(+)-NQR 的改变表达导致还原氧化状态，表现为 NADH、质子动力势（PMF）和 ATP 水平降低。同时，由于还原氧化状态，氯化钠也会负调控 PMF。这些因素共同导致细胞内庆大霉素水平降低，而外部氯化钠水平升高。我们的研究揭示了一种以前未知的、依赖于氯化钠的还原氧化状态相关机制，该机制在弧菌属中影响抗生素耐药性。
