High-Density Cell Culture

The high space-time yields are the result of a doubling time of only 30 min and its applicability for high cell-density cultures. However, it is hardly possible to excrete overexpressed proteins into cultivation media. In addition, accumulation of pyrogenic lipopoly-saccharides in its outer membrane (a distinctive feature of Gram-negative bacteria) make additional purification steps necessary if pharmaceutical proteins are produced by E. coli [29]. 

Choi, D.H. and Keum, K.C. (2006) Production of recombinant proteins by high cell density culture of Pichia pastoris. Chemical Engineering Science, 61, 876-885. 

High cell density culture of R. eutropha has been studied extensively. To maintain glucose concentration within the optimal range, several feeding stra-... 

As summarized above, various approaches were taken to alter the PHA production or to facilitate downstream processing by employing recombinant pseudomonads. However, as in the case with recombinant R. eutropha, no study has been carried out on the high cell density culture of recombinant pseudomonads or on the scale-up of fermentation. 

Honda, H. Sugiyama, H. Saito, I., and Kobayashi, T., High cell density culture of Rhodococcus rhodochrous by pH-stat feeding and dibenzothiophene degradation. Journal of Fermentation and Bioengineering, 1998. 85(3) pp. 334—338. 

Y. L. Lee, H. N. Chang (1990) High cell density culture of a recombinant Escherichia coli producing penicillin acylase in a membrane cell recycle fermentor. Biotechnol. Bioeng., 36 330-337. 

High Cell Density Culture The fed-batch operation that maintains the substrate concentration at a suitable value for a high cell-growth rate can achieve a high cell concentration (50-100gl ). 

S. Y. Lee, High-cell density culture of Escherichia coli, Trends Biotechnol. 1996, 14, 98-105. 

In this way, the use of bioreactors that allow high cell density cultures is of great importance as a tool to increase process productivity. Table 9.3 shows volumetric productivity values that can be obtained in the main types of industrial bioreactors, as well as the typical working volume and the cell concentration ranges that are usually attained. 

Chen, F. 1996. High cell density culture of microalgae in heterotrophic growth. Trends Biotechnol., 14,421 126. 

Kim, B. S. 2006. High cell density culture techniques for production of industrial products. In Hou, C. T. and Shaw, J.-F. (Eds.), Biocatalysis and Biotechnology for Functional Foods and Industrial Products (pp. 505-520). Boca Raton, FL CRC Press. 

Yoon SH, Han M-J, Lee SY et al (2003) Combined transcriptome and proteome analysis of Escherichia coli during high cell density culture. Biotechnol Bioeng 81 753-767... 

Park SJ, Georgiou G, Lee SY. Secretory production of recombinant protein by a high cell density culture of a protease negative mutant Escherichia coli strain. Biotechnol Prog 1999 15(2) 164-167. 

Antoine T, Bosso C, Heyraud A, Samain E. Large scale in vivo synthesis of globotriose and globotetraose by high cell density culture of metabolically engineered Escherichia coli. Biochimie 2005 87 197-203. 

Microencapsulation and encapsulated products have found applications in numerous industries such as agriculture, chemical, pharmaceutical, cosmetic, and food industry over the last century. More recently, applications of these particles in biotechnology and medical processes, including cell encapsulation for artificial implants, production of high cell density cultures and recombinant therapeutic proteins encapsulation as a means for delivery, has opened up a brand new field for this technology. " ... 

Crude pahn kernel oil (CPKO) which is derived from the kernel of the oil palm fruit consists of large amounts of saturated fatty acids such as lauric acid (C12 0) [ 48 %], myristic acid (C14 0) [ 16 %], and palmitic acid (C16 0) [ 8 %] (Loo et al. 2005). However, the concentration of unsaturated fatty acids such as linoleic (C18 2) [ 2 %] is very low. It contrast, palm oil products derived from mesocarp such as crude palm oil (CPO) and palm olein (PO) are mainly composed of C16 0 and contain more unsaturated fatty adds such as oleic acid (C18 l), (C18 2) and trace quantities of Hnolenic add (C18 3) (Loo et al. 2005). Compared to palm oil products, soybean oil is rich in unsaturated fatty adds with C18 2 (54 %), C18 l (22 %), and C18 3 (8 %) as the major constituents while 10 % of the distributions are contributed from saturated fatty adds (Kahar et al. 2004 Loo et al. 2005). Nevertheless, soybean oil has proven to be a good carbon source for high cell density cultures. Since, CPKO contains lesser unsatuiated fatty adds, it conld become potential carbon feedstock for high cell density PHA prodnction. 

A simple, cost-efficient and effective method for the recovery of PHB directly from high cell-density culture broth with no pretreatment steps has been developed by Kim and colleagues. This method consists of direct addition of SDS to the culture broth, shaking, heat treatment, and washing steps. When the SDS/biomass ratio exceeded 0.4, the purity of recovered PHB was over 95% for various cell concentrations. The recovery yield of PHB was over 90% regardless of cell density and SDS concentration the reduction in molecular mass was negligible [79]. 

Slater and co-workers [38] reported that poly[3HB-co-3-hydroxyvalerate (3HV)] could be synthesised by a special mutant (atoC fadR) strain of Escherichia coli LS5218 harbouring the PHA biosynthesis genes of Cupriavidus necator, which enabled the constitutive expression of the enzymes responsible for the utilisation of short-chain fatty acids however, Escherichia coli LS5218 did not produce a high cell density culture. Next, Choi and Lee (1999)... 

---