Whole-cell biocatalysts are versatile tools in (industrial) production processes; though, the effects that impact the efficiency are not fully understood yet. One main factor that affects whole-cell biocatalysts is the surrounding medium, which often consists of organic solvents due to low solubility of substrates in aqueous solutions. It is expected that organic solvents change the biophysical and biochemical properties of the whole-cell biocatalysts, e.g. by permeabilising the cell membrane, and thus analysis of these effects is of high importance. In this work, we present an analysis method to study the impact of organic solvents on whole-cell biocatalysts by means of dielectrophoresis. For instance, we evaluate the changes of the characteristic dielectrophoretic trapping ratio induced by incubation of Escherichia coli, serving as a model system, in an aqueous medium containing isopropyl alcohol. Therefore, we could evaluate the impact on the electric polarisability of the cells. For this purpose, a special microchannel device was designed and Escherichia coli cells were genetically modified to reliably synthesise a green fluorescent protein. We could demonstrate that our method was capable of revealing different responses to small changes in isopropyl alcohol concentration and incubation duration. Complementary spectrophotometric UV-Vis (ultraviolet-visible light) absorbance analysis of released NAD(P)+/NAD(P)H cofactor and proteins confirmed our results. Based on our results, we discuss the biophysical effects taking place during incubation. Graphical abstract.

中文翻译：

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介电泳分析异丙醇对大肠杆菌全细胞电极化的影响。


全细胞生物催化剂是（工业）生产过程中的多功能工具；然而，影响效率的影响尚未完全了解。影响全细胞生物催化剂的主要因素之一是周围介质，由于底物在水溶液中的溶解度较低，周围介质通常由有机溶剂组成。预计有机溶剂会改变全细胞生物催化剂的生物物理和生化性质，例如通过透化细胞膜，因此对这些影响的分析非常重要。在这项工作中，我们提出了一种通过介电泳研究有机溶剂对全细胞生物催化剂影响的分析方法。例如，我们评估了作为模型系统的大肠杆菌在含有异丙醇的水介质中孵育所引起的特征介电泳捕获率的变化。因此，我们可以评估对电池电极化性的影响。为此，设计了一种特殊的微通道装置，并对大肠杆菌细胞进行了基因改造，以可靠地合成绿色荧光蛋白。我们可以证明我们的方法能够揭示对异丙醇浓度和孵育时间的微小变化的不同反应。对释放的 NAD(P)+/NAD(P)H 辅因子和蛋白质的补充分光光度 UV-Vis（紫外-可见光）吸光度分析证实了我们的结果。根据我们的结果，我们讨论了孵化过程中发生的生物物理效应。图形摘要。