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首页> 美国卫生研究院文献>Applied and Environmental Microbiology >Intracellular Changes in Ions and Organic Solutes in Halotolerant Brevibacterium sp. Strain JCM 6894 after Exposure to Hyperosmotic Shock
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Intracellular Changes in Ions and Organic Solutes in Halotolerant Brevibacterium sp. Strain JCM 6894 after Exposure to Hyperosmotic Shock

机译：耐盐短杆菌的离子和有机溶质的细胞内变化。暴露于高渗性休克后的菌株JCM 6894

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In the present study we aimed to observe the intracellular responses when there was a hyperosmotic shock with a large shift in ionic strength in nutrient-rich and nutrient-poor external environments in order to clarify the availability of substrates. To do this, we used the halotolerant organism Brevibacterium sp. strain JCM 6894, which is able to grow in the presence of a wide range of salt concentrations. Hyperosmotic shock was induced by transferring cells in the late exponential phase of growth in a complex medium containing 0.5 M NaCl into either old or fresh culture medium containing 2 M NaCl. Changes in the growth rate, in the pH of the medium, and in the internal cation or organic solute concentrations in the cytosol after an upshock were analyzed as a function of incubation time. The cells exhibited very different responses to upshocks in fresh culture medium and in old culture medium; in fresh culture medium, growth was stimulated and the medium became more acidic, whereas the old culture medium repressed growth and the medium became more alkaline. The intracellular free Na+ concentrations remained low (80 nmol mg of protein−1) after an upshock in fresh culture medium, although they quickly increased twofold in the old culture medium. In contrast, K+ ions immediately accumulated in the cells in fresh culture medium, whereas K+ ions were taken up quite slowly in old culture medium. Furthermore, the cells placed in fresh culture medium transiently accumulated alanine and glutamine in response to the upshock, but the cells placed in old culture medium did not. Growth of the Brevibacterium strain at higher levels of salinity was supported by ectoine synthesis but was not observed after the shift to high-osmolarity conditions in the old culture. In the fresh culture, however, ectoine was vigorously synthesized in cells for more than 5 h after the upshock; the concentration of ectoine in cells was more than 3,500 nmol mg of protein−1 at 10 h, which corresponded to a ninefold increase compared to the concentration before the shock. These findings are consistent with the results of an analysis of the extracellular medium composition before and after the upshock.
机译：在本研究中，我们旨在观察高营养休克时在营养丰富和营养贫乏的外部环境中离子强度发生较大变化的细胞内反应，以阐明底物的可用性。为此，我们使用了可耐盐的生物短杆菌。菌株JCM 6894，能够在宽范围的盐浓度下生长。高渗性休克是通过将处于晚期指数阶段的细胞在含有0.5 M NaCl的复杂培养基中转移到含有2 M NaCl的旧培养基或新鲜培养基中来诱导的。分析了震荡后细胞溶质的生长速率，培养基的pH值以及胞质溶胶中内部阳离子或有机溶质浓度的变化。在新鲜培养基和旧培养基中，细胞对激增反应表现出截然不同的反应。在新鲜培养基中，生长受到刺激，培养基变得更酸性，而旧培养基则抑制生长，而培养基变得更碱性。在新鲜培养基中受到冲击后，细胞内游离Na + 的浓度仍然很低（80 nmol mg蛋白 -1 ），尽管在旧培养基中迅速增加了两倍。相反，K + 离子立即在新鲜培养基中的细胞中积累，而K + 离子在旧培养基中的吸收速度却很慢。此外，放置在新鲜培养基中的细胞响应于震荡而瞬时积累丙氨酸和谷氨酰胺，但是放置在旧培养基中的细胞则没有。短杆菌属菌株在较高盐度下的生长得到了外壁蛋白合成的支持，但在旧培养中转变为高渗透压条件后未观察到。然而，在新鲜培养物中，强烈震荡后5小时以上，细胞中强烈合成了植物素；在10 h时，细胞中的ectoine浓度超过3500 nmol mg蛋白 -1 ，与电击前的浓度相比增加了九倍。这些发现与震荡前后细胞外培养基组成的分析结果一致。

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