Bioreactors Roller bottles

Special reactors are required to conduct biochemical reactions for the transformation and production of chemical and biological substances involving the use of biocatalysts (enzymes, immobilised enzymes, microorganisms, plant and animal cells). These bioreactors have to be designed so that the enzymes or living organisms can be used under defined, optimal conditions. The bioreactors which are mainly used on laboratory scale and industrially are roller bottles, shake flasks, stirred tanks and bubble columns (see Table 1). 

As is the case with pure bubble columns and gas-operated loop reactors, most bioreactors in technical use are aerated with oxygen or air. Reactors with pure surface aeration, such as roller bottles, shake flasks and small stirred reactors or special reactors with membrane aeration, are exceptions. The latter are used for the cultivation of cells and organisms which are particularly sensitive to shearing (see e. g. [28 - 29]). The influence of gas bubbles in increasing stress has been described in many publications (see e.g. [4, 27, 29, 30]). In principle it can be caused by the following processes ... 

Different animal cell types display different properties pertinent to their successful culture. Those used to manufacture biopharmaceuticals are invariably continuous (transformed) cell lines. Such cells will grow relatively vigorously and easily in submerged culture systems, be they roller bottle or bioreactor based. 

Commercial scale cultivation of mammalian cells is accompHshed using different technologies roller bottles, microcarriers, suspension (batch, fed-batch or perfusion mode) and hollow fiber bioreactors (Table 2). However, especially for products needed in large amounts, suspension cultivation seems to be the most effective system [4, 5]. Suspension-based systems are characterized by a homogeneous concentration of cells, nutrients, metabolites and product, thereby facilitating scale-up [6] and enabling an accurate monitoring and control of the culture [7]. 

The range of culture flasks and reactor types employed is quite wide, both for suspension and adherent cultures, from small Carrel s or Roux s flasks to roller bottles. Fixed- and fluidized-bed bioreactors, air-lift reactors and even stirred and aerated tanks with capacities up to 15 m3 are common in large plants producing monoclonal antibodies (mAbs) for anticancer therapies (Adams and Weiner, 2005 Griffiths, 1988). 

Cryotube Stationary flask Roller bottles Production bioreactor... 

Stirred-tank bioreactors Air-lift bioreactors Wave bioreactors Microcarrier-based systems Packed-bed bioreactors Fluidized-bed bioreactors Hollow-fiber bioreactors Bioreactors providing surfaces for attached cell growth (roller bottles, CellCube , Cell Factory)... 

Alternatively, some subunit viral vaccines can be generated by rDNA techniques and expressed in a continuous cell line or insect cells. Recent advances in bio reactor design and operation have improved the successful production of IPV in large-scale bioreactors. However, roller bottles or flasks are still used for most current vaccine production. Development of insect cell culture will allow for very large-scale liquid suspension culture (143). Several vaccine candidates such as gpl60 for HIV and gD protein for herpes have been demonstrated in the insect cell culture system. However, no vaccine has... 

Fig. 6 Various types of animal cell bioreactors (A) roller bottle (B) rotating disk (C) stirred tank with a marine impeller (D) tank with a pulsating agitator (E) stirred tank with a spin filter (F) airlift (G) fluidized bed and (H) hollow fiber. (View this art in color at WWW. dekker. com.)...

Roller bottle reactors have been widely used in the past and can generate cell densities upto 5.4 x 10 cells/ml.However, roller bottles are difficult to scale up and cannot meet the growing demand for therapeutic recombinant proteins. Their popularity is on the decline and are largely replaced by microcarriers, and stirred-tank or airlift bioreactors in process scale-up. Initially, industrial production of EPO by CHO cells is carried out in hundreds of roller bottles in incubation rooms equipped with robots for medium changes and product harvesting. The newer production plant for second-generation EPO employs state-of-the-art bioreactors and has three times the production capacity of the old EPO plant. 

System Roller bottles Stirred-tank reactor Wave bioreactor... 

Roller bottles with 10 L Stirred-tank reactor Wave Bioreactor with... 

Adherent cells can be grown in stationary or microcarrier cultures [116]. Stationary cultures use devices such as flasks, roller bottles, and cell factories that provide wall surface area for cell attachment [117]. Microcarrier cultures, on the other hand, can be implemented in agitated bioreactors [114,116]. These microcarriers are small porous particles (0.2mm) that provide large surface areas for cell attachment and can be suspended in the culture medium by gentle agitation. The culture environment is thus easily controlled and the scale-up is done by increasing the... 

When only small quantities of product are required, scale-up of production via roller bottles in a laboratory robot assisted facility may be feasible, but this approach is susceptible to contamination. Moreover, ensuring uniform environmental conditions throughout a multitude of bottles is not a trivial task. Control of a small stirred tank bioreactor is more readily accomplished. The kinetics of product formation in animal cells can often be represented in terms of the Luedeking-Piret model (see Section 13.1.5). 

Production The production culture may be a batch of several hundred roller bottles, 30 to 50 cell factories, or a single bioreactor for suspension (100 to 10,000 L) or microcarrier (50 to 500 L) ceUs. Although batch-type production is still the most common process, continuous processes where the product is harvested daily over a long period (20 to 100 d) are being increasingly used. Culture systems based on hollow fibers, porous microcarriers, or other immobilization techniques are used for continuous perfusion processes. During the production phase, the virus seed or a promoter (e.g., for interferon) may be added. 

The steps between the cell bank and the production fermentation serve the purpose of expanding the seed volume (biomass) to finally provide sufficient cells to inoculate the main fermenter. Early seed stages, also referred to as precultures, are often run in shake flasks or in T-flasks and roller bottles in the case of cell culture, whereas subsequent stages are performed in stainless steel or single-use bioreactors. The dimensions of the seed bioreactors are adjusted to the biological system, as shown in Table 1.5. 

Roller Bottles Stirred Suspension Bioreactors Wave... 

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