Scale bioreactor

The constant shear concept has been applied for bioreactor scale-up that utilises mycelia, where the fermentation process is shear sensitive and the broth is affected by shear rate of impeller tip velocity. For instance, in the production of novobicin, the yield of antibiotic production is dependent on impeller size and impeller tip velocity. 

Insect cell systems represent multiple advantages compared with mammalian cell cultures (1) they are easier to handle (Table 2.1) (2) cultivation media are usually cheaper (3) they need only minimum safety precautions, as baculovirus is harmless for humans (4) they provide most higher eukaryotic posttranslational modifications and heterologous eukaryotic proteins are usually obtained in their native conformation (5) the baculovirus system is easily scalable to the bioreactor scale. However, because of the viral nature of the system, continuous fermentation for transient expression is not possible - the cells finally die. 

As bioreactor scale-up is usually accomplished by applying geometric similarity... 

It would not be possible to adequately cover the field of stirred tank scale-up in the space available here. Instead, this section will touch briefiy on the important issues in bioreactor scale-up. For more detailed methodologies on stirred tank bioreactor scale-up, the reader is referred to several review papers on the topic (30,37,38). 

Table 2 Antibody Purification Process Scale-Up and Performance for Different Bioreactor Scales...

Product quality and recovery 5000 L Bioreactor scale 350 L Bioreactor scale ... 

Palomares LA, Ramerez OT. In Spier RE, ed. Bioreactor Scale-up, Encyclopedia of Cell Technology. Vol. 1. 2000 183-201. 

As can be observed in Table 9.3, cell concentrations equal to or higher than 107 cells ml-1 are needed to attain volumetric productivities higher than 50 mg L-1 d-1. Also, it is important to note that as cell concentration increases, the complexity of the process increases and, consequently, bioreactor scale-up becomes limited, for example by physical limitations of materials used in hollow-fiber cartridges. 

Rouf SA, Moo-Young M, Scharer JM, Douglas PL (2000), Single versus multiple bioreactor scale-up economy for high-value products, Biochem. Eng. J. 6 25-31. 

Maranga L, Cunha A, Clemente J, Cruz PE, Carrondo MJT (2004), Scale-up of viruslike particles production effects of sparging, agitation and bioreactor scale on cell growth, infection kinetics and productivity, J. Biotechnol. 107 55-64. 

Such information about shear effects in plant cell suspension cultures as given above is useful for bioreactor design and operation as well as the optimization of bioreactor environments for plant cell cultures. It may also be beneficial to bioreactor scale-up and high-density cultivation of plant cells for production of useful plant-specific chemicals (pharmaceuticals). In addition, because different cell suspensions can show different degrees of cell sensitivity to shear stress, and shear affects culture viability, cell lysis, and even metabolite secretion, as demonstrated in various cases like cell cultures of tobacco, Catharanthus roseus and Perilla frutescens [17, 54, 61], detailed studies are required for individual cases. 

Bioreactor scale-up remains a considerable challenge for producers of ERTs. One reason is that pivotal trials for LSDs are conducted on small numbers of patients, using quantities of enzyme that can be produced in smaller bioreactors, before the need to scale up quantities of product (and bioreactor size) to meet commercial demand. This is a conundrum that places considerable pressure on sponsors. The pitfall is that different scales may change the product profile and pharmacokinetics characteristics sufficiently that regulators require duplication of preclinical safety studies and even clinical trials after the pivotal phase 3 trials have been completed. This places an undue burden on sponsors seeking registration for these rare conditions. 

Literature reports have used the following reactor parameters to correlate the effects of agitation intensity with cell injury in bioreactors agitator rpm, impeller tip speed, integrated shear factor and Kolmogorov eddy size. Additional parameters have been used for microcarrier bioreactors (discussed below). All correlations of cell injury with a bioreactor parameter should be used only qualitatively. These correlations are, at present, indicative of various trends or mechanistic hypotheses and should not be used for quantitative bioreactor scale-up. In addition, such correlations are applicable to the specific cell type, because different cell types are likely to exhibit different responses to fluid forces. 

Bourne, I.R. Zurita, E.P. Heinzle, E. Bioreactor scale-up for the oxygen-sensitive culture Bacillus subtilis the influence of stirrer shaft geometry Biotechnol. Prog. 1992, 8 (6), 580-582. 

Flow patterns were visualized by adding tracer particles to the fluid, following the method reported by Espinosa-Solares et al. [11]. x-Carrageenan particle tracers were introduced into the system through the recirculation tube at the top. A digital video camera was used to follow the particle trajectory through the bioreactor. The particle trajectory was drawn using bioreactor-scale sketches. 

Vernardis, S.I., Goudar, C.T., and Klapa, M.I. (2013) Metabolic profiling reveals that time related physiological changes in mammalian cell perfusion cultures are bioreactor scale independent Metah. Eng., 19, 1—9. 

Figure 8.13 Airlift bioreactor scale effects. Adapted from Blazej et al. (2004c).

Garcia-Ochoa, R, and Gomez, E. (2009), Bioreactor scale-up and oxygen transfer rate in microbial processes An overview, Biotechnology Advances, 27(2) 153-176. 

YeUore and Desai (1998) isolated a Methylobacterium sp. ZP24 that grew on cheese whey and produced PHB at a final concentration of 1.1 gP polymer. This work was extended later on a bioreactor scale, where Nath et al. (2008) cultivated this organism on cheese whey. In batch mode, final PHB concentrations of 2.07 gl" ... 

Using the production strain C. necator DSM 545, a final concentration of poly(3HB-co-8.6% 3HV) of 12.7 gl after 62 h of cultivation was described on a 10-1 bioreactor scale. The organism achieved a maximum specific growth rate of 0.14 Ih" (Braunegg et al. 2002). 

Votruba J, Sobotka M. (1992) Physiological similarity and bioreactor scale-up. Folia Microbiol, 37(5) 331-345. 

Garcia-Ochoa F, Gomez E. (2009) Bioreactor scale up and oxygen transferrates in microbial systems an overview. BiotechnoL Adv., 27 153-176. 

Votruba, J., and M. Sobotka. 1992. Physiological Similarity and Bioreactor Scale-Up. Folia Microbiologica 37 (5) 331-345. 

The rate of ATP synthesis is closely related to the type of carbon source. As a strategy to boost SAM synthesis, Hu et al. (2007) report a novel supplement strategy for inducible Pichia. The classical induction period was divided into several 10-h subintervals, and methanol (initial 6 h) and glycerol (subsequent 4 h) were fed alternately during every subinterval. Compared to the typical feeding mode, the novel scheme elevated growth and MAT volumetric activity, while decreased the specific MAT activity. The rate of SAM synthesis within Pichia cells, however, was still improved, mainly due to the enhancement of ATP supply. The switch from methanol to glycerol was invariably associated with inaeased ATP synthesis. SAM synthesis was also favored by an extension of the production period such that SAM content was reputed to be elevated to 13.24 g/L at 5-L bioreactor scale. 

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