Static cultivation

Three different approaches for the cultivation of isolated hematopoietic cells have been described, the static, the stirred and the immobilized culture. Static cultivation takes place in very simple culture systems like well plates, tissue-culture flasks or gas-permeable culture bags [62, 63]. As the first two systems do not allow cell cultivation on a clinical scale, the latter is actually the most often used technique for stem cell expansion. All these systems have the advantage of being easy to handle, single-use devices, which enable an uncomplicated cell harvest. But all of them do not offer possibilities for process control or continuous feeding. This causes variations in culture conditions during fermentation (e.g., oxygen tension, pH, substrate, metabolite and cytokine concentrations). 

This study showed that the bacterial cellulose derived fix)m coconut and pineapple juices can be converted efficiently to bacterial cellulose by the supplementation of yeast extract and ethanol under static fermentation conditions at 30 °C. Bacterial celluloses produced from all strains are growth associated products. Coconut juice seems to be a better substrate than pineapple juice. In view of energy consumption, the productivity of BC on this medium is high, which makes the production costs lower than expected. It is also clear that different A. xylinum strains produce different BC content levels under the same inoculation volumes and under static cultivation conditions. These results suggest that bacterial cellulose pellicles of all strains appear to be easily applied to use in many applications such as food, paper, and textile industries, without requiring additional steps of decolorization and purification. Furthermore, the properties of cellulose, in tenns of crystallinity, high water-absorption capacity, and mechanical strength of the reported strains, have additional applications in cosmetics and medicine. 

Static cultivation is the most common method, from which a highly hydrated BC membrane (or pellicle) on the air-culture medium interface is obtained (Figure 2.2) [19, 38]. As cellulose is synthesized, a membrane with increasing thickness is generated and, once oxygen is required for bacteria growth and cellulose production, it is assumed that the mature BC membrane is constantly pushed down as new cellulose is produced on the interface [8, 15]. 

By the 1970s production techniques had been mastered, seed quality had improved, and simpler hybrids allowed a more reasonable seed price. In addition, fertilizer use increased and irrigation became more sophisticated. Yields increased (Figure 5.3) and the area under cultivation rose dramatically. By 1972, there were 1 800 000 ha of grain corn, and by 1983, there were 1 400 000 ha of com silage. These areas of production have since remained relatively static - primarily as a result of international competition and the resulting fall in prices. 

A classic way to produce viral vaccines consists of cultivating cells on an appropriate static support, infecting them with virus, collecting and purifying the virus produced and formulating the vaccine. 

Ponnudurai, T., Lensen, A. H., Leeuwenberg, A. D., and Meuwissen, J. H. (1982a). Cultivation of fertile Plasmodium falciparum gametocytes in semi-automated systems. 1. Static cultures. Trans. R. Soc. Trap. Med. Hyg. 76,812-818. 

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