Experimental and in silico investigation of population heterogeneity in continuous Sachharomyces cerevisiae scale-down fermentation in a two-compartment setup
Experimental and in silico investigation of population heterogeneity in continuous Sachharomyces cerevisiae scale-down fermentation in a two-compartment setup
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DOI：
10.1002/jctb.4532
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发表时间：
2015-02-01
影响因子：
3.4
通讯作者：
Lantz, Anna Eliasson
中科院分区：
文献类型：
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作者：
Heins, Anna-Lena;Fernandes, Rita Lencastre;Lantz, Anna Eliasson
背景在大型生物反应器中，微生物经常会遇到营养和氧气供应的波动条件，导致不同尺度上的微生物行为不同。根本原因是生产规模的混合能力有限造成的空间异质性。因此，工艺的放大是具有挑战性的，需要能够模拟大规模条件的实验室规模的反应器装置，以增强对波动环境条件如何影响微生物生理的理解。结果采用由两个相互连接的搅拌槽反应器组成的两室缩尺装置，并结合数学模型来模拟大规模连续培养。一个反应器代表高葡萄糖低氧的进料区，而另一个代表剩余的反应器体积。一个早期发展的群体平衡模型与一个非结构化模型相结合，用来描述在不同稀释率、葡萄糖进料浓度以及两室之间回流时间下的体积浓度和细胞大小分布的发展。成功地验证了生物量和葡萄糖的浓度分布。两个荧光报告菌株的单细胞特性被应用于更深层次的细胞稳健性特征和乙醇生长分布的更深入的研究，并被以隔室的方式量化，揭示了与环境条件相关的细胞种群分布的差异，并与单隔室的传统化学恒化器进行了比较。结论结果强调了所提出的组合方法的实用性以及连续缩小反应器在工艺研究中的使用，因为揭示了关于过程的单细胞特征的洞察力，这些洞察力通常是隐藏的。(C)2014年化学工业学会
BACKGROUNDIn large-scale bioreactors, microbes often encounter fluctuating conditions of nutrient and oxygen supply, resulting in different microbial behavior at the different scales. The underlying reason is spatial heterogeneity, caused by limited mixing capabilities at production scale. Consequently, scale-up of processes is challenging and there is a need for laboratory-scale reactor setups that can mimic large-scale conditions to enhance the understanding of how fluctuating environmental conditions affect microbial physiology.RESULTSA two-compartment, scale-down setup, consisting of two interconnected stirred tank reactors was used in combination with mathematical modeling, to mimic large-scale continuous cultivations. One reactor represents the feeding zone with high glucose concentration and low oxygen, whereas the other one represents the remaining reactor volume. An earlier developed population balance model coupled to an unstructured model was used to describe the development of bulk concentrations and cell size distributions at varying dilution rate, glucose feed concentration as well as recirculation times between the two compartments. The concentration profiles of biomass and glucose were successfully validated experimentally. Single cell properties of two fluorescent reporter strains that were applied for deeper investigation of cell robustness characteristics and ethanol growth distributions were quantified compartment-wise revealing differences in cell population distributions related to environmental conditions and also compared with the one-compartment, conventional chemostat.CONCLUSIONResults underline the utility for the proposed combined approach as well as the use of continuous scale-down reactors for process investigations as insights concerning single-cell characteristics of the process are revealed, which are normally hidden. (c) 2014 Society of Chemical Industry