In large-scale bioreactors, gradients in cultivation parameters such as oxygen, substrate, and pH result in fluctuating cell environments. pH fluctuations were identified as a critical parameter for bioprocess performance. Traditionally, scale-down systems at the laboratory scale are used to analyze the effects of fluctuating pH values on strains and thus process performance. Here, we demonstrate the application of dynamic microfluidic single-cell cultivation (dMSCC) as a novel scale-down system for the characterization of Corynebacterium glutamicum growth using oscillating pH conditions as a model stress factor. A detailed comparison between two-compartment reactor (two-CR) scale-down experiments and dMSCC was performed for one specific pH oscillation between reference pH 7 (~8 min) and disturbed pH 6 (~2 min). Similar reductions in growth rates were observed in both systems (dMSCC 21% and two-CR 27%) compared to undisturbed cultivation at pH 7. Afterward, systematic experiments at symmetric and asymmetric pH oscillations, between pH ranges of 4–6 and 8–11 and different intervals from 1 to 20 min, were performed to demonstrate the unique application range and throughput of the dMSCC system. Finally, the strength of the dMSCC application was demonstrated by mimicking fluctuating environmental conditions of a putative large-scale bioprocess, which is difficult to conduct using two-CRs.

中文翻译：

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微流控单细胞按比例缩小生物反应器：在振荡 pH 值下谷氨酸棒杆菌生长的概念验证

在大型生物反应器中，培养参数（如氧气、底物和 pH 值）的梯度会导致细胞环境波动。pH 波动被确定为生物过程性能的关键参数。传统上，实验室规模的按比例缩小系统用于分析 pH 值波动对菌株的影响，从而分析工艺性能。在这里，我们展示了动态微流控单细胞培养 (dMSCC) 作为一种新的按比例缩小系统来表征谷氨酸棒杆菌的应用。使用振荡的 pH 条件作为模型应力因子的生长。针对参考 pH 7（~8 分钟）和受干扰的 pH 6（~2 分钟）之间的一种特定 pH 振荡，对两室反应器（双 CR）按比例缩小实验和 dMSCC 进行了详细比较。与在 pH 7 下未受干扰的培养相比，在两个系统（dMSCC 21% 和双 CR 27%）中观察到类似的生长速率降低。之后，在 4-6 和 8- 之间的对称和不对称 pH 振荡下进行系统实验11 和 1 到 20 分钟的不同时间间隔进行，以展示 dMSCC 系统的独特应用范围和吞吐量。最后，通过模拟假定的大规模生物过程的波动环境条件，证明了 dMSCC 应用的强度，这很难使用两个 CR 进行。