Immobilization plant cell

G. Carturan, R.D. Monte, G. Pressi, S. Secondin, and P. Verza, Production of valuable drugs from plant cells immobilized by hybrid sol-gel Si02. J. Sol-Gel. Sci. Technol. 13, 273—276 (1998). 

Table 7.2 Improved production of secondary metabolites and recombinant proteins by plant cell immobilization.

Immobilization of plant cells in hybrid sol-gel materials. Journal of Sol-Gel Science and Technology, 7, 87-97. 

In recent years, extensive attention has been focused on finding cultured plant cells that can be used as catalysts for organic functional group transformations. A number of transformations employing freely suspended or immobilized plant cell cultures have been reported.24 For example, Akakabe et al.25 report that immobilized cells of Daucus carota from carrot can be used to reduce prochiral carbonyl substrates such as keto esters, aromatic ketones, and heterocyclic ketones to the corresponding secondary alcohols in ( -configuration with enantiomeric excess of 52-99% and chemical yields of 30 63%). 

Other kinds of plant cell cultures such as immobilized tobacco cells have also been studied for the analogous transformation. The results show that plant cell cultures provide an accessible way of converting several prochiral ketones into the corresponding chiral secondary alcohols with reasonable chemical yield and high enantioselectivity. 

Draget KI, Myhre S, Ostgaard K. Plant protoplast immobilized in calcium alginate. A simple method of preparing fragile cells for transmission electron microscopy. Stain Technol 1988 63 159-163. 

Inoculate the flask containing 30 mL of medium with about 30 immobilized plant cell beads and put it in a shaker incubator (150 rpm) at 27°C. Keep the cells dark by blocking the glass window of the incubator. 

Lindsey, K., M. M. Yeoman, G. M. Black, and F. Mavituna, "A novel method for the immobilization and culture of plant cells," FEBS Letters 155 (1983) 143-149. 

Both cell culture with a lipophilic extraction phase and with a polar extraction phase have been reported to be helpful for the accumulation and detection of secondary substances [7,8]. Plant cell cultures release lipophilic and volatile substances such as ethylene, ethanol, and acetaldehyde. The addition of a lipophilic phase to the culture medium can be used as a means of accumulating and detecting these substances. Maisch et al. [8] found that the addition of XAD-4 resin to Nicotiana tabacum cultures enhanced the production of phenolic secondary metabolites several times compared to the adsorbent-free control. Kim and Chang [9] reported in situ extraction for enhanced shikonin production by Lithospermum erythrorhizon. When n-hexadecane was added to the cultivation, higher specific shikonin productivity was obtained than that from the cultures of free cells without extraction. They also suggested that n-hexadecane addition at an early stage in calcium alginate immobilized cell cultures was effective for shikonin production. Most of the produced shikonin was dissolved in n-hexadecane, so it would reduce the costs for shikonin separation. 

Various adsorbents have been examined for their potential to increase in situ product separation in plant cell culture. Suspended solid adsorbents were popular, and the use of immobilized adsorbent has been investigated recently [17-20]. The advantages of immobilized adsorbent are that it is easy to use in a bioreactor operation and that it allows adsorbents to be easily separated from culture broth for the repeated use of cells and adsorbents [21, 22]. The design and optimization of in situ separation process for phytochemicals using immobilized adsorbent required a detailed mathematical model. It was difficult to achieve an optimal design based on purely empirical correlations, because the effects of various design parameters and process variables were coupled. 

In this review the use of adsorbent for the in situ separation of product in plant cell culture is discussed, and a mathematical model which describes immobilized adsorbent coupled with selective separation is presented. Several examples of the application of the technique are also provided. 

The integration of elicitation, in situ product adsorption with XAD-7, and the immobilization of Catharanthus roseus cells lead to an increase in productivity and a significant increase in extracellular ajmalicine production [5]. The integration of in situ product separation by two-phase culture and immobilized plant cells could be feasible for continuous production in immobilized plant cell bioreactors requiring the repeated use of cells. 

Integrated bioprocesses can be used to enhance the production of valuable metabolites from plant cell cultures. The in situ removal of product during cell cultivation facilitates the rapid recovery of volatile and unstable phytochemicals, avoids problems of cell toxicity and end-product inhibition, and enhances product secretion. In situ extraction, in situ adsorption, the utilization of cyclodextrin, and the application of aqueous two-phase systems have been proposed for the integration of cell growth and product recovery in a bioreactor. The simultaneous combination of elicitation, immobilization, permeabilization, and in situ recovery can promote this method of plant cell culture as a feasible method to produce various natural products including proteins. 

Fig. 5. Increased expression of human GM-CSF by immobilized plant cells [76]. Closed symbols indicate normal batch production and open symbols indicate cells encapsulated by alginate. The effects of encapsulation increase the concentration of extracellular protein...

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