Bioreactor stirred-tank reactor

Stirred tank reactor the most common type of bioreactor used in industry. A draught is fitted which provides a defined circulation pattern. 

The main part of the report describes the results of systematic investigations into the hydrodynamic stress on particles in stirred tanks, reactors with dominating boundary-layer flow, shake flasks, viscosimeters, bubble columns and gas-operated loop reactors. These results for model and biological particle systems permit fundamental conclusions on particle stress and the dimensions and selection of suitable bioreactors according to the criterion of particle stress. 

Several other processes were investigated and developed as well, e.g., a) Am-bruticin S production in airlift and stirred tank reactor b) high-cell density cultivation of E. coli and production of rDNA products c) production of thermostable xylanase by Thermomyces lanuginosus d) cultivation of Tetrahymena thermophila in 1.5 bioreactors, e) alginate production by Azotobacter vine-landii. 

Figure 11.9 Different arrangements and modes of operation for membrane bioreactors Continuous Stirred Tank Reactor (CSTR) with recirculation arrangement (a), dead-end cell (b), tubular with entrapped enzyme (c).

The bioreactor has been introduced in general terms in the previous section. In this section the basic bioreactor concepts, i.e., the batch, the fed-batch, the continuous-flow stirred-tank reactor (CSTR), the cascade of CSTRs and the plug-flow reactor, will be described. 

Membrane bioreactors have been reviewed previously in every detail [3,4,7,8,18], There are two main types of membrane bioreactors (i) the system consists of a traditional stirred-tank reactor combined with a membrane separation unit (Figure 14.1) (ii) the membrane contains the immobilized biocatalysts such as enzymes, micro-organisms and antibodies and thus, acts as a support and a separation unit (Figure 14.2). The biocatalyst can be immobilized in or on the membrane by entrapment, gelification, physical adsorption, ionic binding, covalent binding or crosslinking [3, 7, 18]. Our attention will be primarily focused on the second case where the membrane acts as a support for biocatalyst and as a separation unit, in this study. The momentum and mass-transport process, in principle, are the same in both cases, namely when there is... 

The production of substances that preserve the food from contamination or from oxidation is another important field of membrane bioreactor. For example, the production of high amounts of propionic acid, commonly used as antifungal substance, was carried out by a continuous stirred-tank reactor associated with ultrafiltration cell recycle and a nanofiltration membrane [51] or the production of gluconic acid by the use of glucose oxidase in a bioreactor using P E S membranes [52]. Lactic acid is widely used as an acidulant, flavor additive, and preservative in the food, pharmaceutical, leather, and textile industries. As an intermediate product in mammalian metabolism, L( +) lactic acid is more important in the food industry than the D(—) isomer. The performance of an improved fermentation system, that is, a membrane cell-recycle bioreactors MCRB was studied [53, 54], the maximum productivity of 31.5 g/Lh was recorded, 10 times greater than the counterpart of the batch-fed fermentation [54]. 

Various combinations of bioreactors and operation mode have been used for the production of mAbs in several systems of expression, as shown in Chapter 9. All cells utilized for the production of mAbs grow in suspension. Those that did not initially have this capacity have been adapted (as is the case for CHO and BHK) (Butler, 2005). This results in a large number of options for production systems. Cells with this characteristic are easily cultivated in stirred-tank reactors, which have been scaled up to a volume of 10 000 L (Chu and Robinson, 2001 Kretzmer, 2002). This kind of bioreactor provides excellent homogeneity, facility for the implementation of control techniques, and the principles of scaling up are relatively well known. Other kinds of bioreactors for the production of mAbs are also available, such as air-lift, with volumes up to 1000 L, and also fixed-bed bioreactors (Moro et al., 1994 Irving et al., 1996 Kretzmer, 2002). 

Two types of bioreactors are commonly used in industry for performing enzyme-catalyzed transformations the stirred tank reactor and the packed or fluidized bed reactor [28]. Substitution of these weU-established reactors by a system based on microfluidic technology wiU happen only if there are clear and compelling advantages in so doing. It is therefore necessary to consider, in a rigorous and... 

Bioreactors come in many different designs and shapes. The stirred tank reactors are common. They comprise a cylindrical tank, a mechanical stirrer, and a guidance system for the liquid to reduce stress and enhance mixing. Pneumatic reactors use air or oxygen to mix the fermentation broth. The gas is introduced near the bottom of the reactor and induces circulation of the liquid. 

Fig. 9 Bioreactors (A) stirred tank reactor (B) airlift fermenter.

Fig. 1 Bioreactors. (A) activated sludge reactor (B) stirred tank reactor and (C) rotating biofilm reactor. (View this art in color at www.dekker.com.)...

Yahiro et al. [115] conducted itaconic acid production from glucose using stirred-tank and air-lift reactors. Results indicate that the air-lift reactor has a much higher productivity (0.64 g/l/h) than the stirred-tank reactor (0.48 g/l/h). Final itaconic acid concentration reached 65 g/1 after 96 h of fermentation. Likewise, Okabe et al. [116] used an air-lift bioreactor using a modified draft tube for itaconic acid production and obtained an enhanced itaconic acid yield. 

System Roiier botties Stirred-tank reactor Wave bioreactor... 

Roiier botties with 10 L Stirred-tank reactor Wave Bioreactor with... 

Two fundamentally different types of bioreactor setups can be distinguished. In the first type of reactors, MTBE-degradation occurs by bacteria in suspension in continuously stirred tank reactors (CSTR) (Table 6). An obvious advantage of this setup is the optimal mixing of MTBE-degrading biomass, contaminants and oxygen, reducing transport Hmitations to a minimum. However, specialized adaptations are required to prevent washout of biomass from the reactor. Three different methods exist. 

Membrane bioreactors have been modelled using approaches that have proven successful in the more conventional catalytic membrane reactor applications. The simplest membrane bioreactor system, as noted in Chapter 4, consists of two separate units, a bioreactor (typically a well-stirred batch reactor) coupled with an external hollow fiber or tubular or flat membrane module. These reactors have been modelled by coupling the classical equations of stirred tank reactors with the mathematical expressions describing membrane permeation. What makes this type of modelling unique is the complexity of the mecha-... 

These equations remain valid for bioreactors provided that one employs a suitable mathematical representation of the rate of disappearance of the substrate that is the limiting reagent. In Illustration 13.3 we employ an alternative form of the design equation to determine the holding time necessary to achieve a specified degree of conversion in a strictly batch bioreactor. This illustrative example also indicates how overall yield coefficients are employed as a vehicle for taking the stoichiometry of the reaction into account. Illustration 13.4 describes how one type of semibatch operation (the fed-batch mode) can be exploited to combine the potential advantages of batch and continuous flow operation of a stirred-tank reactor. 

There were published several reports about the hyoscyamine production by hairy roots grown in bioreactors [65]. As fare as we are aware there is not enough information about the scopolamine and particularly about 6P-hydroxyhyoscyamine production in these systems. Among them, Hilton and Rhodes [67] studied the hyoscyamine production by D. stramonium in a modified 14 L stirred tank reactor operated imder different conditions in batch and continuous mode. The 35 day culture produced 5.2 mg/g DW and 3.3 mg/g DW of hyoscyamine in Gamborg B5/2 and B5 medium, respectively [67]. B. Candida hairy roots produced a slightly higher amoimt of hyoscyamine. Specifically, the process carried out in the modified stirred tank produced 7.0 1.3 mg/g DW of hyoscyamine at the harvest time (Table 2) [28]. Hilton and Rhodes [67] also reported a low release of the alkaloid into the culture medium. The biomass productivity attained in this work was 0.24 g DW/l/d which is very similar to that reported here for B. Candida hairy root processes (Table 2). 

To choose the adequate bioreactor design for continuous PHA production, kinetics for both biomass and PHA production by the microbial strain should be considered. In the case of PHA production directly associated with microbial growth as it is found in Alcaligenes latus DSM 1122 on sucrose [128], or for Pseudomonasputida ATCC 29147 on fatty acids [97,98], a one-step continuous process using a continuous stirred tank reactor (CSTR) is a viable solution. 

The stirred-tank reactor (STR) is one of the simplest and most widely used bioreactor types. For a preparative resolution of GPE, a mechanieally stirred reactor was operated in batch mode under the above optimal eonditions... 

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