Adaptive responses of Ralstonia eutropha to feast and famine conditions analysed by flow cytometry
Adaptive responses of Ralstonia eutropha to feast and famine conditions analysed by flow cytometry
复制标题
DOI：
10.1016/s0168-1656(99)00130-3
复制
发表时间：
1999-10-08
影响因子：
4.1
通讯作者：
Babel, W
中科院分区：
文献类型：
--
作者：
Müller, S;Bley, T;Babel, W
流式细胞术获得的结果可以得出结论，关于在不同生长条件下，Ralstonia eutropha JMP134的生理状态如何与生存策略相关联。在盛宴和饥荒条件下，细胞都经历了截然不同的生命阶段。选择低碳源（0.02%苯酚）和高碳源（0.2%丙酮酸和0.1%酵母提取物）两种碳源和能量源来研究细胞反应。尽管碳源存在较大差异，但在批量生长中表征细菌在两种基质上的生长阶段时，膜电位相关荧光强度（MPRFI）的时间过程仅存在微小差异。这也适用于细胞的rRNA含量和大小相关的前向散射（FSC）信号，两者在（早期）指数生长阶段都增加到高水平。在富培养基上，DNA合成最初以不偶联的方式进行，然后当营养开始受到限制时，PHB的形成率就会很高。在饥荒条件下，细胞的反应要复杂得多。PHB被合成，然后DNA合成以“真核”模式发生，接着是更新的PHB合成。为了获得明确的细胞生理状态，除批量实验外，还采用了恒化技术。这些结果清楚地表明，细胞生理学中的关键事件，包括DNA复制的起始和溢出代谢，是以一种层次有序的方式发生的，并且与细菌细胞环境条件的变化密切相关。(C) 1999 Elsevier Science B.V.版权所有
Results obtained by flow cytometry allow conclusions to be drawn about how the physiological states of Ralstonia eutropha JMP134 are connected with survival strategies under distinct growth conditions. During both feast and famine conditions the cells were found to proceed through sharply separated phases of life. Two sources of carbon and energy, one poor (0.02% phenol) and one rich (0.2% pyruvate and 0.1% yeast extract) were chosen to study the cellular responses. Despite the major differences in carbon source, when growth stages of the bacteria on the two substrates were characterised in batch growth, only minor differences were found in the time course of the membrane potential related fluorescence intensity (MPRFI). This also applied to the rRNA content and the size-correlated forward scatter (FSC) signal of the cells, both of which increased to high levels during the (early) exponential growth phase. On the rich medium, DNA synthesis initially occurred in an uncoupled manner, then a high rate of PHB formation followed when nutrients began to be limiting. Under famine conditions, the cellular responses were much more complex. PHB was synthesised, then DNA synthesis occurred in a 'eukaryotic' mode, to be succeeded by renewed PHB synthesis. To obtain defined cell physiological states, the chemostat technique was used in addition to batch experiments. The results obtained clearly indicated that key events in cell physiology, including initiation of DNA replication and overflow metabolism, occurred in a hierarchically ordered manner and were tightly correlated with changes in the environmental conditions of the bacterial cells. (C) 1999 Elsevier Science B.V. All rights reserved.