Quantification of power consumption and oxygen transfer characteristics of a stirred miniature bioreactor for predictive fermentation scale‐up

Abstract

Miniature parallel bioreactors are becoming increasingly important as tools to facilitate rapid bioprocess design. Once the most promising strain and culture conditions have been identified a suitable scale-up basis needs to be established in order that the cell growth rates and product yields achieved in small scale optimization studies are maintained at larger scales. Recently we have reported on the design of a miniature stirred bioreactor system capable of parallel operation [Gill et al. (2008); Biochem Eng J 39:164-176]. In order to enable the predictive scale-up of miniature bioreactor results the current study describes a more detailed investigation of the bioreactor mixing and oxygen mass transfer characteristics and the creation of predictive engineering correlations useful for scale-up studies. A Power number of 3.5 for the miniature turbine impeller was first established based on experimental ungassed power consumption measurements. The variation of the measured gassed to ungassed power ratio, P(g)/P(ug), was then shown to be adequately predicted by existing correlations proposed by Cui et al. [Cui et al. (1996); Chem Eng Sci 51:2631-2636] and Mockel et al. [Mockel et al. (1990); Acta Biotechnol 10:215-224]. A correlation relating the measured oxygen mass transfer coefficient, k(L)a, to the gassed power per unit volume and superficial gas velocity was also established for the miniature bioreactor. Based on these correlations a series of scale-up studies at matched k(L)a (0.06-0.11 s(-1)) and P(g)/V (657-2,960 W m(-3)) were performed for the batch growth of Escherichia coli TOP10 pQR239 using glycerol as a carbon source. Constant k(L)a was shown to be the most reliable basis for predictive scale-up of miniature bioreactor results to conventional laboratory scale. This gave good agreement in both cell growth and oxygen utilization kinetics over the range of k(L)a values investigated. The work described here thus gives further insight into the performance of the miniature bioreactor design and will aid its use as a tool for rapid fermentation process development.

Metabolic engineering of Corynebacterium glutamicum for L-arginine production

“…Major considerations include optimizing the culture medium 28 , resolving reduced mass transfer of nutrients in industrial-scale bioreactor 29 and reducing the separation and purification procedure of L-arginine by minimizing byproducts 30 . All these factors substantially affect the overall bioprocess costs, and therefore need to be systematically examined at large-scale, as in the case of pilot-scale cultivation of the AR6 strain conducted in this study.…”

Evaluation of scale-up parameters of bioethanol production from Escherichia coli KO11

“…The oxygen transfer rate can be kept constant by altering stirring speed which concomitantly alters the power input. The use of constant oxygen mass transfer coefficient as scaling criterion is widely applied in conventional scales from laboratory to large scales if there is a strong link between cell growth and dissolved oxygen tension profiles [5]. However if the fermentation broth is viscous, constant mixing time is used through scaling.…”

Hydrodynamic Characteristics of Mechanically Agitated Air - Aqueous Sucrose Solutions

“…The power consumption depends on many factors, among others on the operating parameters of a process and physical parameters of a fluid, as well as the amount of gas supplied to the system. The impact of various parameters on power consumption has been the subject of much research (Adamiak, 2005;Adamiak and Karcz, 2007;Ascanio et al, 2004;Gill et al, 2008;Kamieński, 2004;Karcz and Siciarz, 2001;Markopoulos and Panntuflas, 2001;Nienow and Lilly, 1996;Roman and Tudose, 1997;Stręk, 1981;Vilaca et al, 2000;Yianatos, 2010). Typically adding gas phase to a liquid causes a decrease in power consumption as compared with results achieved for liquid phase alone.…”