Cell culture technology bioreactor

The problems with jojoba as a commercial crop are the usual ones of domestication and cultivation. It is a slow-growing plant, available only in the wild and therefore has very wide genetic variabiUty. Efforts are underway to select the most promising variants and cultivate these as a crop in the southwestern United States deserts (7). A possible alternative for producing jojoba oil is to culture plant embryos in bioreactors (see Cell culture technology). 

A comparison between insect and mammalian cell culture technology shows various similarities and differences. Due to the fact that insect cell lines typically derive from specific organs or non-differentiated embryonic tissues, the same cell line can proliferate in suspension or in adherent manner (in monolayer). This versatility in growth mode, which contrasts with most mammalian cell lines, increases the choices of bioreactor types and culture strategies for production. Contact inhibition shown by various mammalian cell lines is low or absent for insect cells, and they tend to aggregate in suspension or in adherent cultures. 

In spite of these hurdles, the last two decades have seen an immense leap in animal cell culture technology both at the laboratory scale as well as the industrial scale. A variety of bioreactors and instrumentation have been ingeniously been devised for the scale up and process control of animal cell cultures. Serum-free media development has considerably reduced the downstream processing costs in the recombinant protein production and purification process. The capability to induce some cell lines to lose anchorage dependence has also been an important breakthrough. 

Fenge C, LUllau E. (2006) Cell culture bioreactors. In Ozturk SS, Hu WS, editors. Cell culture technology for pharmaceutical and cell-based therapies. Taylor Francis, New York, USA. p 155-224. 

Great progress was achieved in the past decades regarding the development of mammalian cell culture technology [2,34,98-102]. Nevertheless, the design and layout of cultivation systems and bioreactors have to meet cell-specific demands due to the special characteristics of these cells. Selection of a suitable type of cell culture bioreactor system and/or an appropriate operation mode (batch, fed-batch, or perfusion) is affected by technical, biological, economical, and regulatory considerations. 

The 1980 s and the early 1990 s have seen the blossoming development of the biotechnology field. Three-phase fluidized bed bioreactors have become an essential element in the commercialization of processes to yield products and treat wastewater via biological mechanisms. Fluidized bed bioreactors have been applied in the areas of wastewater treatment, discussed previously, fermentation, and cell culture. The large scale application of three-phase fluidized bed or slurry bubble column fermen-tors are represented by ethanol production in a 10,000 liter fermentor (Samejima et al., 1984), penicillin production in a 200 liter fermentor (Endo et al., 1986), and the production of monoclonal antibodies in a 1,000 liter slurry bubble column bioreactor (Birch et al., 1985). Fan (1989) provides a complete review of biological applications of three-phase fluidized beds up to 1989. Part II of this chapter covers the recent developments in three-phase fluidized bed bioreactor technology. 

Rhizosecretion is easy to scale up and very cost effective with respect to isolation and purification. However, the bioreactor systems used for hairy root cultures differ from those used for plant cell suspensions. Traditional bioreactor systems have recently been adapted for root culture, and this technology is now being taken to commercial scales. The most traditional system is the airlift bioreactor used for microorganisms or plant cells. This system is adapted for the culturing of roots in liquid medium. Mist culture systems have also been developed. For this technology, the volume of the culture medium is reduced and the concentration of the secreted therapeutic protein is increased. If the protein to be produced is known to be quite stable, then a less expensive hydroponic culture can be designed in a manner suitable for scale-up. 

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