Pappenreiter Magdalena, Sissolak Bernhard, Sommeregger Wolfgang, Striedner Gerald
R&D - Bilfinger Industrietechnik Salzburg GmbH, Salzburg, Austria.
Department of Biotechnology (DBT), University of Natural Resources and Life Sciences (BOKU), Vienna, Austria.
Front Bioeng Biotechnol. 2019 Aug 21;7:195. doi: 10.3389/fbioe.2019.00195. eCollection 2019.
In aerobic cell cultivation processes, dissolved oxygen is a key process parameter, and an optimal oxygen supply has to be ensured for proper process performance. To achieve optimal growth and/or product formation, the rate of oxygen transfer has to be in right balance with the consumption by cells. In this study, a 15 L mammalian cell culture bioreactor was characterized with respect to under varying process conditions. The resulting dynamic description combined with functions for the calculation of oxygen concentrations under prevailing process conditions led to an easy-to-apply model, that allows real-time calculation of the oxygen uptake rate (OUR) throughout the bioprocess without off-gas analyzers. Subsequently, the established OUR soft-sensor was applied in a series of 13 CHO fed-batch cultivations. The OUR was found to be directly associated with the amount of viable biomass in the system, and deploying of cell volumes instead of cell counts led to higher correlations. A two-segment linear model predicted the viable biomass in the system sufficiently. The segmented model was necessary due to a metabolic transition in which the specific consumption of oxygen changed. The aspartate to glutamate ratio was identified as an indicator of this metabolic shift. The detection of such transitions is enabled by a combination of the presented dynamic OUR method with another state-of-the-art viable biomass soft-sensor. In conclusion, this hyphenated technique is a robust and powerful tool for advanced bioprocess monitoring and control based exclusively on bioreactor characteristics.
在需氧细胞培养过程中，溶解氧是一个关键的过程参数，必须确保最佳的氧气供应以实现良好的过程性能。为了实现最佳生长和/或产物形成，氧气传递速率必须与细胞的消耗保持适当平衡。在本研究中，对一个15 L的哺乳动物细胞培养生物反应器在不同工艺条件下的 进行了表征。由此产生的动态 描述与在当前工艺条件下计算氧气浓度的函数相结合，形成了一个易于应用的模型，该模型无需废气分析仪即可在整个生物过程中实时计算氧气摄取率（OUR）。随后，将建立的OUR软传感器应用于13次CHO补料分批培养。发现OUR与系统中活生物质的量直接相关，使用细胞体积而非细胞计数可得到更高的相关性。一个两段线性模型足以预测系统中的活生物质。由于代谢转变导致氧气的比消耗发生变化，因此需要分段模型。天冬氨酸与谷氨酸的比例被确定为这种代谢转变的一个指标。通过将所提出的动态OUR方法与另一种先进的活生物质软传感器相结合，可以检测到这种转变。总之，这种联用技术是一种强大而稳健的工具，仅基于生物反应器特性即可用于先进的生物过程监测和控制。
