Biocatalysts immobilized

End N, Schoning K-U (2004) Immobilized Biocatalysts in Industrial Research and Production. 242 273-317... 

Kokufuta, E. Novel Applications for Stimulus-Sensitive Polymer Geb in the Preparation of Functional immobilized Biocatalysts, Vol, 110, pp. 157-178. 

Itoh, N., Nakamura, M., Inoue, K. and Makino, Y. (2007) Continuous production of chiral 1,3-butanediol using immobilized biocatalysts in a packed bed reactor promising biocatalysis method with an asymmetric hydrogen-transfer bioreduction. Applied Microbiology and Biotechnology, 75 (6), 1249-1256. 

Chibata, L., Tosa, T. and Shibatani, T. (1992) The industrial production of optically active compounds by immobilized biocatalysts, in Chirality in Industry (eels A. X. Collins, G.N. Sheldrake and J. Crosby), John Wiley Sons, Ltd, New York, pp. 351-370. 

To improve biocatalyst recovery and ease of recycle, a research group reported immobilization of Gordona strain CYKS1 on celite beads [197], A cell loading of 1.5 mg cell/g celite was obtained. Use of immobilized biocatalyst at 50% v/v relative to aqueous buffer volume probably results in higher cell density however, the specific rate of desulfurization appeared to decrease. The reports did not have sufficient data to correctly... 

A procedure for immobilization of a P. stutzeri UP-1 strain using sodium alginate was reported [133], This strain does not perform sulfur-specific desulfurization, but degrades DBT via the Kodama pathway. Nevertheless, the report discussed immobilization of the biocatalyst cells in alginate beads with successful biocatalyst recovery and regeneration for a period of 600 h. However, the immobilized biocatalyst did decrease in specific activity, although the extent of loss was not discussed. The biocatalyst was separated after every 100 h of treatment, washed with saline and a boric acid solution and reused in subsequent experiment. The non-immobilized cells were shown to loose activity gradually with complete loss of activity after four repeat runs of 20 hour each. The report does not mention any control runs, which leaves the question of DBT disappearance via adsorption on immobilized beads unanswered and likewise the claim of a better immobilized biocatalyst. 

AET has also demonstrated very high operational thermal stability for immobilized biocatalysts, which is applicable to a multitude of industrial areas including the biocat-alytic and biosensor industries. 

More specifically, the invention involves the use of Thiobacillus denitrificans under anaerobic conditions to oxidize sulfur compounds such as hydrogen sulfide to sulfate. The process may be carried out in various ways such as in a batch or a continuous bioreactor system using a suspended or an immobilized biocatalyst. The method is particularly applicable to treating natural gas containing hydrogen sulfide and producing a biomass byproduct. 

The methods developed by EBC and others in the late 1990s using hydrocyclones and phase-inversion techniques may be sufficient for separation of the treated oil from the aqueous phase and biocatalyst. However, a cost analysis of such methods may be necessary to determine the economic feasibility. Recent work using hydrophobic membranes, magnetically separable immobilized biocatalysts and other techniques may provide alternate methods for separation of oil and recycling biocatalyst. A comparison of these techniques with each other and the previously investigated hydrocyclone techniques is needed to demonstrate improvements in the separation efficiency. 

L. D. Bowers, Applications of immobilized biocatalysts in chemical analysis, Anal. Chem. 58, 513A-530A (1986). 

Ballesteros et defined immobilized biocatalysts as enzymes, cells or organelles (or combinations of these) which are in a state that permits their reuse . Enzyme immobilization represents only a small part of this field, but is the most commonly employed in pharmaceutical production. 

Ballesteros, A., van Beynum, G., Bomd, O. and Buchholz, K., Guidelines for the characterization of immobilized biocatalysts. Enzyme Microb. TechnoL, 1983, 5, 304-307. 

For some recent reviews, see Pfenosil, J.E., Kut, O.M., Dunn, I.J. and Heinzle, E., Immobilized biocatalysts. In Ullman s Biotechnology and Biochemical Engineering, vol. 2. Wiley-VCH, Weinheim, 2007, pp. 683-734 Sheldon, R. A., Enzyme immobilization the quest for optimum performance. Adv. Synth. Catal., 2007, 349, 1289-1307 End, N. and Schoning, K.-U., Immobilized biocatalysts in industrial research and production. Topics Curr. Chem., 2004, 242, 273-317 Bornscheuer, U.T., Immobilizing enz3mies how to create more suitable biocatalysts. Angew. Chem. Int. Ed., 2003,42, 3336-3337 Cao, L. Immobilised enzymes science or art Curr. Opin. Chem. Biol., 2005, 9, 217-226. 

The one-pot dynamic kinetic resolution (DKR) of ( )-l-phenylethanol lipase esterification in the presence of zeolite beta followed by saponification leads to (R)-l phenylethanol in 70 % isolated yield at a multi-gram scale. The DKR consists of two parallel reactions kinetic resolution by transesterification with an immobilized biocatalyst (lipase B from Candida antarctica) and in situ racemization over a zeolite beta (Si/Al = 150). With vinyl octanoate as the acyl donor, the desired ester of (R)-l-phenylethanol was obtained with a yield of 80 % and an ee of 98 %. The chiral secondary alcohol can be regenerated from the ester without loss of optical purity. The advantages of this method are that it uses a single liquid phase and both catalysts are solids which can be easily removed by filtration. This makes the method suitable for scale-up. The examples given here describe the multi-gram synthesis of (R)-l-phenylethyl octanoate and the hydrolysis of the ester to obtain pure (R)-l-phenylethanol. 

The use of CLEA preparations of commercially available HNLs allowed for the enantiocomplementary production of cyanohydrins from a pyridinecarboxaldehyde at a much higher chiral purity than had previously been demonstrated with any chemical catalyst. The key to the success of this process was the use of the CLEA -immobilized biocatalysts that allowed reaction conditions to be chosen to minimize the negative effects of the nonspecific background reaction. 

Tanaka A, Tetsuya T, Kobayashi T (1993) Industrial application of immobilized biocatalysts. Marcel Dekker, New York Rosenthaler L (1908) Biochem Z 14 238 Becker W, Pfeil E (1966) J Am Chem Soc 88 4299... 

Tanaka, A., Tosa, T. and Kobayashi, T. (eds.) (1993) Industrial application of immobilized biocatalysts. New York Marcel Dekker Inc. 

In general the use of immobilized biocatalysts makes continuous processes possible. This facilitates process control, which optimizes product yield and quality. Other advantages of immobilized biocatalysts are 1) that they do not become mixed with the product, which makes product recovery easier and 2) that the biocatalyst, in the case of enzymes, usually becomes more stable. 

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