Culture optimising

The carbohydrate (again often molasses, 15 - 25%) and added nutrients are pH-adjusted to below 4.0 and, for Otis process, have to be sterilised. It is necessary to add potassium hexacyanoferrate but greater care is required in this process compared to surface culture. The A. niger seems to be more sensitive to and more easily inhibited by hexacyanoferrate in submerged culture. It is essential however to lower the ferrous and manganese concentrations, probably below 200 and 5 pg l1 respectively, to optimise the performance of A. niger. 

Plants modified to have higher content of polyphenols for use by the food industry or for production of dietary supplements will become available together with polyphenol mixtures produced by cell cultures. However, in order to benefit from such production of optimised mixtures for food use, a... 

Some laboratories have found an alternative to the short-term cultures by using cell lines other than Caco-2 cells. The most popular of these is Madin-Darby canine kidney (MDCK) cells, an epithelial cell line from the dog kidney. MDCK cells have been suggested to perform as well as Caco-2 cells in studies of passive drug permeability [56]. These cells have also been used to optimise the conditions for studies of low-solubility drugs [53]. However, as noted previously, the active transport processes of this cell line can be quite different to those of Caco-2 cells [28-30], Another cell line that only requires short-term culture is 2/4/A1, which is a conditionally immortalised rat intestinal epithelial cell line [86]. The 2/4/A1 cell line is discussed in Section 4.3.2.2 below. 

Weber, W, Weber, E., Geisse, S. and Memmert, K. (2002). Optimisation of protein expression and establishment of the Wave Bioreactor system for Baculovirus/insect cell culture. Cytotechnology 38, 77-85. 

In Section 2, factors that could lead to particle assembly and secretion into the supernatant were discussed. At this point a deeper analysis of the factors affecting cell infection will be made. Optimisation of the production process should take into account virus-cell interactions, and more specifically viral attachment and internalisation into the cell. The impact of chemical modifications of the medium in baculovirus attachment-internalisation has not been carefully studied. It is widely known for example, that serum increases the infec-tivity of baculovirus. These reviewers have had one case where we were only able to succeed in infecting Sf9 cells adapted to growth in serum-free media [52], with a baculovirus produced by Sf9 cells (not adapted to grow in serum-free media), after adding serum to the culture (authors unpublished observations). However, since serum is not desirable for use in industrial production, its utilisation should be avoided as much as possible. 

The content of desired enzymes at the end of fermentation processes should be as high as possible in order to ease the downstream processing. This may be achieved by a proper choice of microorganisms, optimising the fermentation conditions (e.g. culture media, inducer, morphology, growth rate) or by RDNA technology. 

For each solution, the question will be asked "What is needed for realisation ". By this means, the necessary "hard" and "soft" pre-conditions will be determined (e.g. new partners, specialists, choice of business management, different company culture,. ..) In a further step, these pre-conditions defined are further described by a timeframe "When will it be possible " During discussion, tasks necessary to clarify pre-conditions will be continually noted. Wherever there are potential improvements described, which cannot be optimised in-house, links to new business models like Chemical Leasing are established. 

Lor most of this work, optimised in vitro plant cell suspension cultures were used, especially from R. serpentina and C. roseus, and in the latter case, differentiated tissue (seedling) was also successfully used for investigation of various aspects of vindoline biosynthesis [12, 13]. 

While these examples illustrate the role of flow cytometry in bioprocess monitoring, the analyses have been conducted off-line thus making their use in bioprocess control impractical. Recently, a portable flow cytometer - the Microcyte - [148] has been described, which due to its small size and lower cost (compared to conventional machines) allows flow cytometry to be used as an at-line technique [149]. Ronning showed that this instrument had a role to play in the determination of viability of starter cultures and during fermentation. The physiological status of each individual cell is likely to be an important factor in the overall productivity of the culture and is therefore a key parameter in optimising production conditions. 

Gomes, J., Gomes, I., Terler, K., Gubala, N., Ditzelm A. G., and Steiner, W., Optimisation of culture medium and conditions for a-l-Arabinofuranosidase production by the extreme thermophilic eubacterium Rhodothermus marinus. Enzyme Microbial Technol 2000, 27 (6), 414-422. 

Schneider YJ (1989) Optimisation of hybridoma cell growth and monoclonal antibody secretion in a chemically defined, serum- and protein-free culture medium. 

Louren o da Silva A, Marc A, Engasser JM Goergen JL (1996) Kinetic model of hybridoma cultures for the identification of rate limiting factors and process optimisation. Mathematics Computers in Simulation 1277 1-9. 

Looby D Griffiths JB (1987) Optimisation of glass sphere immobilised bed cultures. In Spier RE Griffiths JB (eds) Modern Approaches to Animal Cell Technology, pp. 342-452. Butterworth, Guildford. 

Mammalian cell cultures producing high-value biopharmaceuticals are expensive and time-consurning to study due to their exclusive dependence on experimentation. A mathematical model has been developed that describes batch/fed-batch hybridoma suspension cultures under normal and chemically-arrested conditions, which is also used to optimise the fed-batch cultures. The optimised strategy was tested experimentally demonstrating that product concentration was closely predicted though the viable cell concentration was partly underestimated. Overall, the model has assisted in reducing the number of experiments required to determine optimal cell culture conditions. Further work is required to improve the model predictability. 

Cell Cycle Modelling for Off-line Dynamic Optimisation of Mammalian Cultures... 

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