Bioreactor mixing efficiency modulates the activity of a prpoS::GFP reporter gene in E. coli.
Bioreactor mixing efficiency modulates the activity of a prpoS::GFP reporter gene in E. coli.
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DOI：
10.1186/1475-2859-8-15
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发表时间：
2009-02-25
影响因子：
6.4
通讯作者：
Thonart P
中科院分区：
文献类型：
--
作者：
Delvigne F;Boxus M;Ingels S;Thonart P
广泛的研究表明，生物过程的放大对微生物的生理学有重大影响。在与生物反应器流体动力学相关的因素中，随着规模的增大而导致的全局混合效率的丧失所引起的浓度梯度是导致微生物种群水平上强烈的生理变化的主要现象。由于涉及到复杂的生理机制，这些变化还没有完全被理解。在这项工作中，我们打算在单细胞水平上研究与大肠杆菌应激反应相关的rpos基因的表达。报道菌株的培养已经在一个小规模的反应器中进行，以及在一系列能够随着规模的增加而诱导细胞外扰动的缩小的生物反应器中进行。基于绿色荧光蛋白(GFP)合成的转录报告基因的目的是监测rpos的水平。已经观察到，GFP水平在从批次到补料批次阶段的过渡过程中增加。在这种最初的增加之后，细胞的绿色荧光蛋白含量下降，主要是由于细胞分裂的稀释。然而，如果使用分隔式生物反应器，GFP含量会显著下降，因为混合条件很差，导致细胞暴露在周期性和随机的胞外波动中。如果考虑到细胞对细胞GFP含量的流式细胞术图谱，这种下降必须归因于微生物群体中GFP含量水平上的分离。胞外扰动的产生(在目前的情况下，在糖浓度和溶解氧水平上)导致了rpos表达水平的下降。这一下降必须归因于微生物种群中的分离现象，主要亚群表现出低表达水平，而次要亚群保持其初始高表达水平。分离的强度及其在培养过程中出现的时间与生物反应器的混合效率有关。
Extensive studies have shown that up-scaling of bioprocesses has a significant impact on the physiology of the microorganisms. Among the factors associated with the fluid dynamics of the bioreactor, concentration gradients induced by loss of the global mixing efficiency associated with the increasing scale is the main phenomena leading to strong physiological modifications at the level of the microbial population. These changes are not fully understood since they involve complex physiological mechanisms. In this work, we intend to investigate, at the single cell level, the expression of the rpoS gene associated with the stress response of E. coli. The cultures of the reporter strain have been performed in a small scale reactor as well as in a series of scaled-down bioreactors able to induce extracellular perturbations with increasing level of magnitude. The rpoS level has been monitored by the aim of a transcriptional reporter gene based on the synthesis of the green fluorescent protein (GFP). It has been observed that the level of GFP increases during the transition from batch to fed-batch phase. After this initial increase, the GFP content of the cell drops, primarily due to the dilution by cell division. However, a significant drop of the GFP content has been observed if using a partitioned bioreactor, for which the mixing conditions are very bad, leading to the exposure of the cells to cyclic and stochastic extracellular fluctuations. If considering the flow cytometric profile of the cell to cell GFP content, this drop has to be attributed to the appearance of segregation at the level of the GFP content among the microbial population. The generation of extracellular perturbations (in the present case, at the level of the sugar concentration and the dissolved oxygen level) has led to a drop at the level of the rpoS expression level. This drop has to be attributed to a segregation phenomenon in microbial population, with a major sub-population exhibiting a low expression level and a minor sub-population keeping its initial elevated expression level. The intensity of the segregation, as well as its time of appearance during the culture can be related to the bioreactor mixing efficiency.
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影响因子：
2.9
作者：
Delvigne, F;Lejeune, A;Thonart, P
通讯作者：
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