Scale‐Up and Scale‐Down Methodologies for Bioreactors

Neubauer, Peter; Junne, Stefan

doi:10.1002/9783527683369.ch11

Cited by 37 publications

(35 citation statements)

References 112 publications

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“…The successful operation of a scale‐down bioreactor to study a particular process depends on how accurately the scale‐down bioreactor mimics the environmental heterogeneity existing in the large‐scale bioreactor. Although multi‐compartment scale‐down bioreactors can provide comprehensive information on cellular responses (Neubauer & Junne, ; Neubauer & Junne, ), they are complex to operate and not easy to parallelize for early screening approaches.…”

Section: Introductionmentioning

confidence: 99%

A model‐based framework for parallel scale‐down fed‐batch cultivations in mini‐bioreactors for accelerated phenotyping

Anane

García

Haby

et al. 2019

Biotech & Bioengineering

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Concentration gradients that occur in large industrial‐scale bioreactors due to mass transfer limitations have significant effects on process efficiency. Hence, it is desirable to investigate the response of strains to such heterogeneities to reduce the risk of failure during process scale‐up. Although there are various scale‐down techniques to study these effects, scale‐down strategies are rarely applied in the early developmental phases of a bioprocess, as they have not yet been implemented on small‐scale parallel cultivation devices. In this study, we combine mechanistic growth models with a parallel mini‐bioreactor system to create a high‐throughput platform for studying the response of Escherichia coli strains to concentration gradients. As a scaled‐down approach, a model‐based glucose pulse feeding scheme is applied and compared with a continuous feed profile to study the influence of glucose and dissolved oxygen gradients on both cell physiology and incorporation of noncanonical amino acids into recombinant proinsulin. The results show a significant increase in the incorporation of the noncanonical amino acid norvaline in the soluble intracellular extract and in the recombinant product in cultures with glucose/oxygen oscillations. Interestingly, the amount of norvaline depends on the pulse frequency and is negligible with continuous feeding, confirming observations from large‐scale cultivations. Most importantly, the results also show that a larger number of the model parameters are significantly affected by the scale‐down scheme, compared with the reference cultivations. In this example, it was possible to describe the effects of oscillations in a single parallel experiment. The platform offers the opportunity to combine strain screening with scale‐down studies to select the most robust strains for bioprocess scale‐up.

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Section: Introductionmentioning

confidence: 99%

A model‐based framework for parallel scale‐down fed‐batch cultivations in mini‐bioreactors for accelerated phenotyping

Anane

García

Haby

et al. 2019

Biotech & Bioengineering

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“…In these processes, cells are constantly exposed to oscillating concentrations of substrate, metabolites, dissolved oxygen and carbon dioxide. Hence, the study of performance under conditions similar to industrial scale process is essential to increase scale‐up reliability and speed up process development . The effects of oscillating cultivation conditions on microbial physiology and product yields have been studied in the laboratory by applying scale‐down techniques, either in the form of scale‐down bioreactors or as pulse‐based methods …”

Section: Introductionmentioning

confidence: 99%

“…These operation mechanisms produce zones similar to feeding and starvation zones in large‐scale bioreactors and result in periodic exposure of the culture to varying stresses . Scale‐down techniques have been applied for the successful study of the impact of large‐scale gradients for most industrially relevant organisms, with significant differences in process behaviour compared with standard small‐scale cultivations …”

Section: Introductionmentioning

confidence: 99%

“…Hence, the study of performance under conditions similar to industrial scale process is essential to increase scale-up reliability and speed up process development. 1,2 The effects of oscillating cultivation conditions on microbial physiology and product yields have been studied in the laboratory by applying scale-down techniques, either in the form of scale-down bioreactors [3][4][5][6] or as pulse-based methods. [7][8][9][10] A scale-down system is a laboratory-scale bioreactor designed to mimic the environmental conditions in large-scale bioreactors.…”

Section: Introductionmentioning

confidence: 99%

“…15 Scale-down techniques have been applied for the successful study of the impact of large-scale gradients for most industrially relevant organisms, with significant differences in process behaviour compared with standard small-scale cultivations. 1,12,16,17 The most recent advances in the development of scale-down concepts include the coupling of computational fluid dynamics (CFD) models of bioreactors with cellular growth kinetics (cellular reaction dynamics, CRD) [18][19][20][21] and the mechanistic description of population groups in heterogeneous environments. 22,23 The CFD-CRD models have been used to define specific stress exposure times that are assumed to occur at the larger scale, based on mixing characteristics (CFD simulations) and the dynamics of cellular responses.…”

Section: Introductionmentioning

confidence: 99%

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Modelling concentration gradients in fed‐batch cultivations of E. coli – towards the flexible design of scale‐down experiments

Anane

Sawatzki

Neubauer

et al. 2018

J of Chemical Tech & Biotech

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BACKGROUND The impact of concentration gradients in large industrial‐scale bioreactors on microbial physiology can be studied in scale‐down bioreactors. However, scale‐down systems pose several challenges in construction, operation and footprint. Therefore, it is challenging to implement them in emerging technologies for bioprocess development, such as in high throughput cultivation platforms. In this study, a mechanistic model of a two‐compartment scale‐down bioreactor is developed. Simulations from this model are then used as bases for a pulse‐based scale‐down bioreactor suitable for application in parallel cultivation systems. RESULTS As an application, the pulse‐based system model was used to study the misincorporation of non‐canonical branched‐chain amino acids into recombinant pre‐proinsulin expressed in Escherichia coli, as a response to oscillations in glucose and dissolved oxygen concentrations. The results show significant accumulation of overflow metabolites, up to 18.3% loss in product yield and up to 10‐fold accumulation of the non‐canonical amino acids norvaline and norleucine in the product in the pulse‐based cultivation, compared with a reference cultivation. CONCLUSIONS Results indicate that the combination of a pulse‐based scale‐down approach with mechanistic models is a very suitable method to test strain robustness and physiological constraints at the early stages of bioprocess development. © 2018 Society of Chemical Industry

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Computational fluid dynamics simulation improves the design and characterization of a plug‐flow‐type scale‐down reactor for microbial cultivation processes

Mayer

Cserjan‐Puschmann

Haslinger

et al. 2022

Biotechnology Journal

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The scale-up of bioprocesses remains one of the major obstacles in the biotechnology industry. Scale-down bioreactors have been identified as valuable tools to investigate the heterogeneities observed in large-scale tanks at the laboratory scale. Additionally, computational fluid dynamics (CFD) simulations can be used to gain information about fluid flow in tanks used for production. Here, we present the rational design and comprehensive characterization of a scale-down setup, in which a flexible and modular plug-flow reactor was connected to a stirred-tank bioreactor. With the help of CFD using the realizable k-ε model, the mixing time difference between a 20 and 4000 L bioreactor was evaluated and used as scale-down criterion. CFD simulations using a shear stress transport (SST) k-ω turbulence model were used to characterize the plugflow reactor in more detail, and the model was verified using experiments. Additionally, the model was used to simulate conditions where experiments technically could not be performed due to sensor limitations. Nevertheless, verification is difficult in this case as well. This was the first time a scale-down setup was tested on high-cell-density Escherichia coli cultivations to produce industrially relevant antigen-binding fragments (Fab). Biomass yield was reduced by 11% and specific product yield was reduced by 20% during the scale-down cultivations. Additionally, the intracellular Fab fraction was increased by using the setup. The flexibility of the introduced scale-down setup in combination with CFD simulations makes it a valuable tool for investigating scale effects at the laboratory scale. More information about the large scale is still necessary to further refine the setup and to speed up bioprocess scale-up in the future.

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Scale‐Up and Scale‐Down Methodologies for Bioreactors

Cited by 37 publications

References 112 publications

A model‐based framework for parallel scale‐down fed‐batch cultivations in mini‐bioreactors for accelerated phenotyping

A model‐based framework for parallel scale‐down fed‐batch cultivations in mini‐bioreactors for accelerated phenotyping

Modelling concentration gradients in fed‐batch cultivations of E. coli – towards the flexible design of scale‐down experiments

Computational fluid dynamics simulation improves the design and characterization of a plug‐flow‐type scale‐down reactor for microbial cultivation processes

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