Can genetically modified Escherichia coli with neutral buoyancy induced by gas vesicles be used as an alternative method to clinorotation for microgravity studies?
Can genetically modified Escherichia coli with neutral buoyancy induced by gas vesicles be used as an alternative method to clinorotation for microgravity studies?
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DOI：
10.1099/mic.0.27062-0
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发表时间：
2005-01-01
期刊：
影响因子：
2.8
通讯作者：
Klaus, D
中科院分区：
文献类型：
--
作者：
Benoit, M;Klaus, D
太空飞行已被证明会影响各种细菌生长参数。有人提出，失重可以使细胞保持均匀分布，从而改变其周围液体的化学组成，从而间接影响它们的生理行为。为了支持这一论点，使用倾斜仪部分模拟微重力下获得的静止环境的地面研究通常在模拟实际空间条件下报告的反应的细菌生长特征方面取得了成功。这里提出了一种新的方法，通过使用经过基因改造的中性浮力的大肠杆菌培养物来评估减少细胞沉降量的效果。由于回转不会(或只会最小程度地)影响这个已经接近胶体的细胞系统的细胞分布，因此假设相对于静态对照，对最终种群密度的影响将被消除。在摇床和静态条件下培养产生气泡的大肠埃希菌，并比较了60英寸的培养密度。作为对照，不产生气泡但在其他方面与实验菌株相同的大肠杆菌也在回转器和静态条件下培养。根据假设，在60h时，旋转和静态产生气泡的大肠杆菌的细胞密度没有显著差异，而不产生气泡的细胞的平均种群密度增加了10.5%(P=0.0001)。这些结果进一步表明，在非搅拌的体外培养中，缺乏累积的细胞沉淀物是太空飞行的主要影响。
Space flight has been shown to affect various bacterial growth parameters. It is proposed that weightlessness allows the cells to remain evenly distributed, consequently altering the chemical makeup of their surrounding fluid, and hence indirectly affecting their physiological behaviour. In support of this argument, ground-based studies using clinostats to partially simulate the quiescent environment attained in microgravity have generally been successful in producing bacterial growth characteristics that mimic responses reported under actual space conditions. A novel approach for evaluating the effects of reduced cell sedimentation is presented here through use of Escherichia coli cultures genetically modified to be neutrally buoyant. Since clinorotation would not (or would only minimally) affect cell distribution of this already near-colloidal cell system, it was hypothesized that the effects on final population density would be eliminated relative to a static control. Gas-vesicle-producing E coli cultures were grown under clinostat and static conditions and the culture densities at 60 In were compared. As a control, E coli that do not produce gas vesicles, but were otherwise identical to the experimental strain, were also grown under clinostat and static conditions. As hypothesized, no significant difference was observed in cell populations at 60 h between the clinorotated and static gas-vesicle-producing E coli cultures, while the cells that did not produce gas vesicles showed a mean increase in population density of 10(.)5% (P=0(.)001). These results further suggest that the lack of cumulative cell sedimentation is the dominant effect of space flight on non-stirred, in vitro E coli cultures.