Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, Massachusetts, USA.
Biotechnol J. 2024 Feb;19(2):e2300384. doi: 10.1002/biot.202300384.
A new biomanufacturing platform combining intracellular metabolic engineering of the oleaginous yeast Yarrowia lipolytica and extracellular bioreaction engineering provides efficient bioconversion of plant oils/animal fats into high-value products. However, predicting the hydrodynamics and mass transfer parameters is difficult due to the high agitation and sparging required to create dispersed oil droplets in an aqueous medium for efficient yeast fermentation. In the current study, commercial computational fluid dynamic (CFD) solver Ansys CFX coupled with the MUSIG model first predicts two-phase system (oil/water and air/water) mixing dynamics and their particle size distributions. Then, a three-phase model (oil, air, and water) utilizing dispersed air bubbles and a polydispersed oil phase was implemented to explore fermenter mixing, gas dispersion efficiency, and volumetric mass transfer coefficient estimations (k a). The study analyzed the effect of the impeller type, agitation speed, and power input on the tank's flow field and revealed that upward-pumping pitched blade impellers (PBI) in the top two positions (compared to Rushton-type) provided advantageous oil phase homogeneity and similar estimated k a values with reduced power. These results show good agreement with the experimental mixing and k a data.
一种新的生物制造平台，结合了产油酵母解脂耶氏酵母的细胞内代谢工程和细胞外生物反应工程，为高效地将植物油/动物脂肪转化为高价值产品提供了可能。然而，由于需要高搅拌和通气来在水介质中创建分散的油滴以实现有效的酵母发酵，因此很难预测流体动力学和传质参数。在当前的研究中，商业计算流体动力学（CFD）求解器 Ansys CFX 与 MUSIG 模型相结合，首先预测了两相系统（油/水和空气/水）的混合动力学及其粒径分布。然后，采用三相模型（油、空气和水）利用分散的气泡和多分散的油相来探索发酵罐的混合、气体分散效率和体积传质系数（k a）的估算。该研究分析了搅拌器类型、搅拌速度和功率输入对罐内流场的影响，结果表明，顶部两个位置的上吸式斜叶搅拌器（PBI）（与 Rushton 式相比）提供了有利的油相均一性，并具有相似的估计 k a 值，但功率降低。这些结果与实验混合和 k a 数据吻合较好。
