High Cell-Density Cultivation

Sletta, H., Aune, R., Nedal, A. etal. (2007) The presence of N-terminal secretion signal sequences leads to strong stimulation of the total expression levels of three tested medically important proteins during high-cell-density cultivations of Pichia pastoris. Applied and Environmental Microbiology, 73 (3), 906-912. 

High Cell-Density Cultivation of Escherichia coli with Surface-Anchored Transglucosidase... 

Wu, P.-H., Nair, G.R., Chu, I.-M. and Wu, W.-T. (2008) High cell density cultivation of Escherichia coli with surface anchored transglucosidase for use as whole-cell biocatalyst for a-arbutin synthesis. Journal of Industrial... 

Much effort has been made to use recombinant strains of E. coli, which expressed the PHA biosynthesis genes from R. eutropha, or other combinations of a suitable host organism and foreign PHA biosynthesis genes for high cell density cultivation and production of bulk amounts of PHAs. The interested reader is referred to a different chapter of this book [13] and the references cited therein in which these systems are described in detail. 

The Application of a 2D-Spectrofluorometer for the Monitoring of High-Cell-Density Cultivations... 

High cell densities are not only a prerequisite for high productivity additionally an effective on-line control and modeling of the bioprocesses is necessary. For industrial applications, optical measurement methods are more attractive because they are non-invasive and more robust. The potential of the BioView sensor for on-line bioprocess monitoring and control was tested. For high-cell-density cultivation of Escherichia coli, maintaining aerobic conditions and removal of inhibitory by-products are essential. Acetic acid is known to be one of the critical metabolites. Information about changes in the cell metabolism and the time of important process operations is accessible on-line for optimization... 

Fig. 4. Courses of culture fluorescence diu-ing a high-cell-density cultivation of . coli...

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 9.19 shows typical cell concentrations reached in the main industrial bioreactors and a comparison of these values with those found in microbial fermentations. As can be observed, batch and fed-batch cultivations attain dry biomass values comparable to those of continuous cultures of microorganisms, so that mass and heat transfer capacities are not limited for these operation modes. However, high cell density cultivation in heterogeneous bioreactors, such as hollow-fiber devices, reaches dry biomass values similar to the maxima observed in microbial cultures. 

Lee, S. Y., Wong, H. H., Choi, J., Lee, S. H., Lee, S. C., and Han, C. S. 2000. Production of medium-chain-length polyhydroxyalkanoates by high-cell-density cultivation of Pseudomonas putida under phosphorus limitation. Biotech. Bioeng., 68,466-410. 

Xia X-X, Han M-J, Lee SY et al (2008) Comparison of the extracellular proteomes of Escherichia coli B and K-12 strains during high cell density cultivation. Proteomics... 

High Cell Density Cultivations of GFP Producing Bacillus megaterium. 141... 

In a project implemented at Nil, ovine growth hormone (oGH) was expressed as inclusion bodies using a pQE expression vector. The expressed protein was 10 -15% of the total cellular proteins of E. coli. The recombinant ovine growth hormone was purified from inclusion bodies and refolded into its native conformation. The refolded recombinant oGH was found to be immunoreactive with RIA/RRA characterized by SDS-PAGE, Western blot, N-terminal amino acid sequence, CD, fluorescence spectra, RIA, and RRA. High cell density cultivation was standardized and found to be enhanced to 100 times. In 16 h, 3.2 g H of oGH was produced which is claimed to be the highest level of any recombinant growth hormone reported in E. coli [57]. 

Another interesting alternative in future, already under investigation, could be a high cell density cultivation and use of microalgae biomass having a much lower content of lignin in comparison to the plant materials mentioned in Table 5.6. 

Four kinds of PHA, P(3HB), P(3HB-co-3HV), P(3HB-co-4HB), and P(3HB-co-3HHx), are produced on a large scale from 1000 to 50 000 tons per year for commercial exploitation. The annual production of 5000 tons is estimated to cost from US 3.5 to US 4.5 per kg. For reduction of production cost, high cell density cultivation, super-high rate of... 

Riesenberg D, Guthke R (1999) High-cell-density cultivation of microorganisms. Appl Microbiol Biotechnol 51 422-430... 

Genzela Y, Vogela T, Buck J, Behrendt I, Ramirez DV, Schiedner G. Jordan I, Reichl U. High cell density cultivations by alternating tangential flow (ATE) perfusion for influenza A virus production using suspension cells. Vaccine 2014 32 2770-2781... 

---