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Epping MS, Wedde S, Grundmann A, Radukic M, Gröger H, Hummel A, Viefhues M. Dielectrophoretic analysis of the impact of isopropyl alcohol on the electric polarisability of Escherichia coli whole-cells. Anal Bioanal Chem 2020; 412:3925-3933. [PMID: 32157360 PMCID: PMC7235074 DOI: 10.1007/s00216-020-02451-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 01/13/2020] [Accepted: 01/23/2020] [Indexed: 12/18/2022]
Abstract
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.
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Affiliation(s)
- Miriam S Epping
- Experimental Biophysics and Applied Nanosciences, Department of Physics, Bielefeld University, 33615, Bielefeld, Germany
| | - Severin Wedde
- Industrial Organic Chemistry and Biotechnology, Department of Chemistry, Bielefeld University, 33615, Bielefeld, Germany
- Fermentation Engineering, Department of Technology, Bielefeld University, 33615, Bielefeld, Germany
| | - Armin Grundmann
- Experimental Biophysics and Applied Nanosciences, Department of Physics, Bielefeld University, 33615, Bielefeld, Germany
| | - Marco Radukic
- Experimental Biophysics and Applied Nanosciences, Department of Physics, Bielefeld University, 33615, Bielefeld, Germany
- Cellular and Molecular Biotechnology, Department of Technology, Bielefeld University, 33615, Bielefeld, Germany
| | - Harald Gröger
- Industrial Organic Chemistry and Biotechnology, Department of Chemistry, Bielefeld University, 33615, Bielefeld, Germany
| | - Anke Hummel
- Industrial Organic Chemistry and Biotechnology, Department of Chemistry, Bielefeld University, 33615, Bielefeld, Germany
| | - Martina Viefhues
- Experimental Biophysics and Applied Nanosciences, Department of Physics, Bielefeld University, 33615, Bielefeld, Germany.
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