Slouka Christoph, Wurm David J, Brunauer Georg, Welzl-Wachter Andreas, Spadiut Oliver, Fleig Jürgen, Herwig Christoph
Research Division Biochemical Engineering, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria.
Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, Institute of Chemical Engineering, Vienna University of Technology, Vienna 1060, Austria.
Sensors (Basel). 2016 Nov 11;16(11):1900. doi: 10.3390/s16111900.
New approaches in process monitoring during industrial fermentations are not only limited to classical pH, dO₂ and offgas analysis, but use different in situ and online sensors based on different physical principles to determine biomass, product quality, lysis and far more. One of the very important approaches is the in situ accessibility of viable cell concentration (VCC). This knowledge provides increased efficiency in monitoring and controlling strategies during cultivations. Electrochemical impedance spectroscopy-EIS-is used to monitor biomass in a fermentation of BL21(DE3), producing a recombinant protein using a fed batch-based approach. Increases in the double layer capacitance (C), determined at frequencies below 1 kHz, are proportional to the increase of biomass in the batch and fed batch phase, monitored in offline and online modes for different cultivations. A good correlation of C with cell density is found and in order to get an appropriate verification of this method, different state-of-the-art biomass measurements are performed and compared. Since measurements in this frequency range are largely determined by the double layer region between the electrode and media, rather minor interferences with process parameters (aeration, stirring) are to be expected. It is shown that impedance spectroscopy at low frequencies is a powerful tool for cultivation monitoring.
工业发酵过程监测的新方法不仅局限于传统的pH、溶解氧和尾气分析，还采用基于不同物理原理的各种原位和在线传感器来测定生物量、产品质量、细胞裂解等更多参数。其中一个非常重要的方法是活细胞浓度（VCC）的原位可及性。这一知识在培养过程的监测和控制策略中提高了效率。电化学阻抗谱（EIS）用于监测BL21(DE3)发酵过程中的生物量，该菌株采用补料分批培养法生产重组蛋白。在低于1kHz频率下测定的双层电容（C）的增加与分批培养和补料分批培养阶段生物量的增加成正比，在不同培养过程中以离线和在线模式进行监测。发现C与细胞密度具有良好的相关性，为了对该方法进行适当验证，进行并比较了不同的先进生物量测量方法。由于在该频率范围内的测量很大程度上由电极与介质之间的双层区域决定，预计与过程参数（曝气、搅拌）的干扰较小。结果表明，低频阻抗谱是培养监测的有力工具。
