Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA.
Department of Biochemical Engineering, University College London, London, UK.
Biotechnol Bioeng. 2021 Mar;118(3):1199-1212. doi: 10.1002/bit.27643. Epub 2020 Dec 21.
The methylotrophic yeast Pichia pastoris is widely used as a microbial host for recombinant protein production. Bioreactor models for P. pastoris can inform understanding of cellular metabolism and can be used to optimize bioreactor operation. This article constructs an extensive macroscopic bioreactor model for P. pastoris which describes substrates, biomass, total protein, other medium components, and off-gas components. Species and elemental balances are introduced to describe uptake and evolution rates for medium components and off-gas components. Additionally, a pH model is constructed using an overall charge balance, acid/base equilibria, and activity coefficients to describe production of recombinant protein and precipitation of medium components. The extent of run-to-run variability is modeled by distributions of a subset of the model parameters, which are estimated using the maximum likelihood method. Model prediction from the extensive macroscopic bioreactor model well describes experimental data with different operating conditions. The probability distributions of the model predictions quantified from the parameter distribution are quantifiably consistent with the run-to-run variability observed in the experimental data. The uncertainty description in this macroscopic bioreactor model identifies the model parameters that have large variability and provides guidance as to which aspects of cellular metabolism should be the focus of additional experimental studies. The model for medium components with pH and precipitation can be used for improving chemically defined medium by minimizing the amount of components needed while meeting cellular requirements.
甲醇营养型酵母毕赤酵母被广泛用作微生物宿主来生产重组蛋白。毕赤酵母生物反应器模型可以帮助我们理解细胞代谢，并可用于优化生物反应器的操作。本文构建了一个广泛的毕赤酵母宏观生物反应器模型，用于描述基质、生物质、总蛋白、其他培养基成分和废气成分。通过引入物种和元素平衡来描述培养基成分和废气成分的吸收和演化速率。此外，还使用总电荷平衡、酸碱平衡和活度系数构建了一个 pH 模型，用于描述重组蛋白的生产和培养基成分的沉淀。通过对模型参数子集的分布进行建模来模拟运行间的可变性程度，这些参数使用最大似然法进行估计。广泛的宏观生物反应器模型的预测与不同操作条件下的实验数据吻合良好。从参数分布中定量得出的模型预测的概率分布与实验数据中观察到的运行间可变性具有定量一致性。该宏观生物反应器模型中的不确定性描述确定了具有较大可变性的模型参数，并为确定应将细胞代谢的哪些方面作为额外实验研究的重点提供了指导。具有 pH 和沉淀的培养基成分模型可用于通过最小化所需成分的数量来改进化学成分确定的培养基，同时满足细胞需求。
