Nepal Sudip, Kumar Pradeep
Department of Physics, University of Arkansas, Fayetteville, AR 72701, USA.
Microelectronics and Photonics Graduate Program, University of Arkansas, Fayetteville, AR 72701, USA.
Microorganisms. 2020 Apr 27;8(5):637. doi: 10.3390/microorganisms8050637.
We perform quantitative studies of the growth, death, and gene expression of in a wide range of magnesium sulfate (MgSO 4 ) concentrations (0-2.5 M). Elevated concentration of MgSO 4 causes the inhibition of cell growth, leading to an increase in the population doubling time. We find that cells exhibit three distinct morphological phenotypes-(i) normal, (ii) filamentous, and (iii) small cells at 1 . 25 M MgSO 4 . Filamentous cells arise due to the lack of cell division, while the small cells arise due to the partial plasmolysis of the cells. We further find that cell death starts for salt concentrations >1.25 M and increases with an increasing concentration of MgSO 4 . For salt concentrations ≥1.66 M, the growth of cells stops and all the cells become smaller than the control cells, suggesting the plasmolysis of the population. Cells grown at salt concentration up to 2 . 07 M are reversible in both the growth rate and morphology upon the removal of the salt stress. The time scale of reversibility increases with increasing salt concentration. Finally, we investigate the expression of an osmotically inducible gene (), genes involved in magnesium transport (), sulfate transport (), and osmotically driven transport of water (). We find that a high concentration of magnesium sulfate leads to the upregulation of and .
我们对处于广泛硫酸镁（MgSO₄）浓度范围（0 - 2.5 M）内的[具体对象未给出]的生长、死亡和基因表达进行了定量研究。硫酸镁浓度升高会导致细胞生长受到抑制，从而使群体倍增时间增加。我们发现，在1.25 M MgSO₄浓度下，细胞呈现出三种不同的形态表型——（i）正常型，（ii）丝状型，以及（iii）小型细胞。丝状细胞的出现是由于细胞分裂缺失，而小型细胞的出现是由于细胞的部分质壁分离。我们进一步发现，当盐浓度>1.25 M时细胞死亡开始，并随着MgSO₄浓度的增加而增加。对于盐浓度≥1.66 M，细胞生长停止，所有细胞变得比对照细胞小，这表明群体发生了质壁分离。在盐浓度高达2.07 M下生长的细胞，在去除盐胁迫后，其生长速率和形态都是可逆的。可逆性的时间尺度随着盐浓度的增加而增加。最后，我们研究了一个渗透诱导基因（[具体基因未给出]）、参与镁转运的基因（[具体基因未给出]）、硫酸盐转运的基因（[具体基因未给出]）以及水的渗透驱动转运的基因（[具体基因未给出]）的表达。我们发现高浓度的硫酸镁会导致[具体基因未给出]和[具体基因未给出]的上调。
