Use of Immobilized Cells

It is possible to carry out experiments with immobilized cells in essentially nonaqueous media (Rothenburger and Atlas 1993), and this could prove an attractive strategy for compounds with limited water solubility, provided that solvents can be found that are compatible with the solubility of the substrate and the sensitivity of the cells to organic solvents. 

Encapsulated cells have been successfully used for the commercial biosynthesis of a number of valuable compounds such as amino acids, and this technique could readily be 

With appropriate experimental modifications, the varions procednres could be adapted to study biodegradation nnder anaerobic conditions. For example, sparging with air could be replaced by the use of a gas mixture containing appropriate concentrations of CO2 and H2 in an inert gas snch as N2. 

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The use of immobilized cell reactors have shown improved biocatalyst stability, however, the specific rates of desulfurization have been much lower than for suspended cell (stirred) reactors. Mass transfer limitations have been significant resulting in lower rates. Thus, the activity is sacrificed to achieve stability. Further work in this area and improved immobilization matrices can help improve the activity along with the stability. 

Chibata I, Tosa T (1981) Use of immobilized cells. Arum Rev Biophys Bioeng 10 197-216... 

The use of immobilized cell technology in beer production has recently been reviewed (Mensour et al, 1997). Industrial processes for maturation of beer and production of alcohol free beer are now in operation. 

The use of immobilized cell systems is applicable to all fermentation schemes and is being researched extensively for the production of alcohols, chemicals, and biological products. 

Margaritis, A. and Bajpai, P., Continuous ethanol production from Jerusalem artichoke tubers. II. Use of immobilized cells of Kluyveromyces marxianus, Biotechnol. Bioeng., 24, 1483-1493, 1982c. 

The use of immobilized cells opens the possibility of keeping the produced biomass in the reactor and using it for prolonged periods of time, under the constraint that the product is excreted by the cells. A disadvantage is the possible occurrence of mass transport limitations inside the biomass beads or in the biofilm. Much of the technology to realize a large-scale process with immobilized cells has yet to be developed, and it might well turn out to be economically unfeasible in most cases. 

Studies on the use of immobilized cells in microbial transformations have continued and the 1,2-dehydrogenation activity of Nocardia rhodocrous ° and... 

Nevertheless, industrial use of immobilized cells is still limited and it will depend on the development of processes that can be readily scaled up. Data available in the literature on materials and techniques used for viable cell immobilization for application in alcoholic beverages and food-grade ethanol production are highlighted and discussed. 

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