Batch culture systems

Heyndrickx, M., De Vos, P., Thibau, B., Stevens, P., and De Ley, J. 1987. Effect of various external factors on the fermentative production of hydrogen gas from glucose by Clostridium butyricum strains in Batch culture. System. Appl. Microbiol., 9,163-168. 

The biofermenter BF-F500 system consisted of a 1.5 1 culture vessel, 2 1 medium reservoir and effluent bottle (2 1 glass vessels) for fresh and expended media which were connected to the perfusion (culture) vessel by a peristaltic pump. As shown in Fig. 14, the fermenter systems have a conical shape sedimentation column in the center of the fermenter, and an impeller on the bottom of the sedimentation column. The Namalwa cells, KJM-1, were cultivated by continuous cultivation in the biofermenter. In Fig. 15, the culture has been inoculated at 1 to 2 x 10 cells/ml with an initial flow rate of approximately 10 ml/h, sufficient to support the population growth. At densities of 7 x 10 -1.5 x 10" cells/ml, we have used a nutrient flow rate of 1340 ml/h using ITPSG and ITPSG-F68 serum-free media. The flow rate of fresh media was increased step-wise from 240 to 960 ml/d in proportion to the increase in cell density. This resulted in an increase of 4 to 10 fold in cell density compared to the conventional batch culture systems. This system was then scaled up to a 45 1 SUS316L unit mounted on an auto-sterilization sequence system with a medium reservoir and an effluent vessel of 901 each. 

As the consequence of this, the metabolic waste products are initially distributed evenly in the bulk medium but accumulated with time in batch culture systems. Furthermore, as a part of normal culture operations, the vessels are taken out from the incubator for microscopic observations, which can cause movement of the bulk medium and formation of temperature gradients, consequently contributing to forced and natural convection, respectively. In industrial-scale bioreactors, the applied perfusion creates forced convection, which is the primary mode of mass transfer. The common feature of all the conventional systems, laboratory- or industrial scale, is that due to the long distances and the large medium volume in comparison with the cell volume, the significance of convection is pronounced. Consequently, mass transfer in such systems takes place in all directions (x-, y- and z-direction) with a comparable magnitude, as is schematically shown in Fig. 2a. 

Batch culture systems consisted of 125-mL Erlenmeyer flasks containing 50 mL MSM and 100 mg/L alachlor. The flasks were inoculated directly with 0.5 g of soil from simulated chemical spill experiments or with 1 mL aliquots of soil suspensions (1 g soil/10 mL H2O). The flasks were incubated on a rotary shaker at 25°C for up to 4 weeks with periodic sampling for microbial isolation. 

Fermenter Type of traditional hioreactor (stirred or nonstirred tanks) where ceU fermentation takes place. Fermenters can he operated as continuous or batch-culture systems. In a continuous culture, nutrients are continuously fed into the fermenta-... 

It has been reported that a high yield of 3HB (96%) can be obtained within a relatively short time (30 min) in Alcaligenes lotus by using a fed-batch culture system with sucrose as a carbon source. The cells with stored PHB were collected and incubated at pH 4 and 37 °C to provide an environmental condition in which cells exhibit high activity of intracellular PHA depolymerase and low activity of (R)-(-)-3-hydro q butyric acid dehydrogenase. Other identified factors that contribute in in vivo depolymerization are substrate concentration and extracellular pH. Ren et reported that the optimal initial pH range for initiation of intracellular depolymerization of PHA by Pseudomonas putida was 8-11, and pH 11 after commencing... 

Commercial-scale operations are conducted in batch, fed-batch, or continuous culture systems. Fermentation vessels include the conventional baffled aerated tank, with or without impeller agitation, and the ak-lift tower fermentors in which ak is sparged into an annular space between the... 

Continuous processes have lower labor costs but have higher failure risk. Batch processes can be started back up in a shorter period of time than can a complex continuous process. Batch processes are easier to take through the regulatory process than are continuous processes. Thus batch processes are often chosen for mammalian ceU culture systems, even though continuous processes can offer significant cost advantages. CeU culture costs constitute only a smaU (10—30%) fraction of the overaU cost of making a product. 

As you might have already gathered, the majority of industrial fermentations are batch processes. In closed batch systems, the growth medium is inoculated with cells and growth and product formation is allowed to proceed until the required amount of conversion has taken place. After harvesting the culture the vessel is cleaned, sterilised and filled with fresh medium prior to inoculation. For some processes, addition of all the feedstock prior to inoculation, as is done in closed batch fermentations, is undesirable and it is preferable to incrementally add the carbon source as the fermentation proceeds. Such a process is known as fed-batch culture and the approach is often used to extend the lifetime of batch cultures and thus product yields fed-batch cultures are considered further in Section 2.7.4. 

Figure 2.5 Possible technological solutions to bioprocess problems a) Fed-batch culture b) Continuous product removal (eg dialysis, vacuum fermentation, solvent extraction, ion exchange etc) c) Two-phase system combined with extractive fermentation (liquid-impelled loop reactor) d) Continuous culture, internal multi-stage reactor e) Continuous culture, dual-stream multi-stage reactor f) Continuous culture with biomass feedback (cell recycling). (See text for further details).

False. Continuous culture systems are more difficult to operate than batch cultures. Medium is continuously added and withdrawn, making the process more prone to contamination. Maintenance cannot be carried out during lengthy culture runs, making the equipment more prone to breakdown. Batch cultures do not suffer such drawbacks. 

The production-scale fermentation unit, with a projected annual capacity of over50,000 tonnes was fully commissioned in 1980. The bioreactor (Figure 4.8) is 60 m high, with a 7 m base diameter and working volume 1,500 m3. There are two downcomers and cooling bundles at the base. Initial sterilisation is with saturated steam at 140°C followed by displacement with heat sterilised water. Air and ammonia are filter sterilised as a mixture, methanol filter sterilised and other nutrients heat sterilised. Methanol is added through many nozzles, placed two per square metre. For start-up, 20 litres of inoculum is used and the system is operated as a batch culture for about 30 h. After this time the system is operated as a chemostat continuous culture, with methanol limitation, at 37°C and pH 6.7. Run lengths are normally 100 days, with contamination the usual cause of failure. 

Batch fermentation is the most widely used method of amino add production. Here the fermentation is a dosed culture system which contains an initial, limited amount of nutrient. After the seed inoculum has been introduced the cells start to grow at the expense of the nutrients that are available. A short adaptation time is usually necessary (lag phase) before cells enter the logarithmic growth phase (exponential phase). Nutrients soon become limited and they enter the stationary phase in which growth has (almost) ceased. In amino add fermentations, production of the amino add normally starts in the early logarithmic phase and continues through the stationary phase. 

The procedure for the estimation of qs and qp is identical to the one presented for fed-batch and continuous cultures. The only difference is in the estimation of the specific growth rate (p). Since perfusion cultures behave as batch cultures as far as the biomass is concerned, p can be obtained as described earlier for batch systems. Namely p is obtained as the slope in the plot of / Xv(t,) versus t,. 

Andersen et al. (1996) and Andersen (1995) have studied the effect of temperature on the recombinant protein production using a baulovinis/insect cell expression system. In Tables 17.15, 17.16, 17.17, 17.18 and 17.19 we reproduce the growth data obtained in spinner flasks (batch cultures) using Bombyx mori (Bm5) cells adapted to serum-free media (Ex-Cell 400). The working volume was 125 ml and samples were taken twice daily. The cultures were carried out at six different incubation temperatures (22, 26,28, 30 and 32 TT). 

Takeuchi, K., Koike, K. and Ito, S. (1990) Production of ris-unsaturated hydrocarbons by a strain of Rhodococcus in repeated batch culture with a phase-inversion, hollow fiber system. Journal of Biotechnology, 14, 179-186. 

The medium composition used in the fed-batch process was optimized, resulting in cell densities near 100 g l-1. By using an exponential feed rate resulting in a growth rate of 0.05 h-1, a maximum biomass concentration of 112 g 1 1 was attained, with a biomass productivity of 1.8 g 1 1 h. The poly(3HAMCL) productivity however was low, 0.34 g 1 1 h, caused by a steady decrease of the poly(3HAMCL) content during the last part of the fermentation [51]. When this optimized medium composition was used in the continuous culture system described above, a maximum biomass concentration of 18 g 1 1 was reached. The PHA content however remained low at approximately 10% [51]. It is still unclear what causes these low PHA contents. 

In order to reduce the time required to confirm the accumulation of a given recombinant protein, we have developed a cell culture system in which transgenic alfalfa callus material produced at the proliferation step of Agrobacterium-based transformation is used to initiate cell cultures. These cell suspensions can be subcultured to sustain batch production of modest protein amounts. The protein blot shown in Fig. 1.2 demonstrates our ability to detect a recombinant protein in total... 

Fed-batch cultures differ from batch cultures by the possibility of additional input of the main substrate. Potentially, fed-batch cultures are very promising since in these cultures the possibility to prolong a hydrogen production phase with approximately constant rate exists. Unfortunately publications reporting the application of this cultivation regime for hydrogen production systems are not known to us. 

Batch latex manufacturing, 14 721 Batch membrane system, 21 638 Batch microcarrier cell culture systems, 5 350, 352-354... 

Batch stirred tank H SCL/oleum aromatic sulfonation processes, 23 541 Batch stirred tank SO3 sulfonation processes, 23 543 Batch structural models, 20 705 Batch sulfonation, 74 387 Batch suspension cell culture systems, 5 349-352... 

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