Biocatalysis industrial processes

These perspectives allow us to conclude that the constant rise of importance of biocatalysis in industrial processes is secured for years to come, and is limited only by further recognition from industrial society. 

Romagnoli LG, Knorr D (1988) Effects of ferulic acid treatment on growth and flavor development of cultured Vanilla planifolia cells. Food Biotechnol 2 93-104 Schrader J, Etschmann MMW, Sell D, Hilmer J-M, Rabenhorst J (2004) Applied biocatalysis for the synthesis of natural flavour compounds—current industrial processes and future prospects. Biotechnol Lett 26 463-472... 

Further advantages of biocatalysis over chemical catalysis include shorter synthesis routes and milder reaction conditions. Enzymatic reactions are not confined to in vivo systems - many enzymes are also available as isolated compounds which catalyze reactions in water and even in organic solvents [28]. Despite these advantages, the activity and stability of most wild-type enzymes do not meet the demands of industrial processes. Fortunately, modern protein engineering methods can be used to change enzyme properties and optimize desired characteristics. In Chapter 5 we will outline these optimization methods, including site-directed mutagenesis and directed evolution. 

In the case of biocatalysis, enzymes [3] and catalytic antibodies [4] have attracted most attention. Since enzymes are inherently the more active catalysts, they have been used most often. Indeed, many industrial processes for the enantioselective production of certain chiral intermediates are based on the application of enzymes, as in the lipase-catalyzed kinetic resolution of an epoxy-ester used in the production of the anti-hypertensive therapeutic Diltiazem [5]. Recently, it has been noted that there seems to be a trend in industry to use enzymes more often than in the past... 

Sime, J. T. Applications of Biocatalysis to Industrial Processes, J. Chem. Educ. 1999, 76, 1658-1661. 

Whole-cell based biocatalysis utilizes an entire microorganism for the production of the desired product. One of the oldest examples for industrial applications of whole-cell biocatalysis is the production of acetic acid from ethanol with an immobilized Acetobacter strain, which was developed nearly 200 yr ago. The key advantage of whole-cell biocatalysis is the ability to use cheap and abundant raw materials and catalyze multistep reactions. Recent advances in metabolic engineering have brought a renaissance to whole-cell biocatalysis. In the following sections, two novel industrial processes that utilize whole-cell biocatalysis are discussed with emphasis on the important role played by metabolic engineering. 

Pohl M, Liese A. Industrial processes using lyases for C-C, C-N, and C-C bond formation. In Biocatalysis in the Pharmaceutical and Biotechnology Industries, Ed. Patel RN. CRC Press, Boca Raton, FL, 2007, p. 661. 

Enzymes have been naturally tailored to perform under physiological conditions. However, biocatalysis refers to the use of enzymes as process catalysts under artificial conditions (in vitro), so that a major challenge in biocatalysis is to transform these physiological catalysts into process catalysts able to perform under the usually tough reaction conditions of an industrial process. Enzyme catalysts (biocatalysts), as any catalyst, act by reducing the energy barrier of the biochemical reactions, without being altered as a consequence of the reaction they promote. However, enzymes display quite distinct properties when compared with chemical catalysts most of these properties are a consequence of their complex molecular stracture and will be analyzed in section 1.2. Potentials and drawbacks of enzymes as process catalysts are summarized in Table 1.1. 

It is evident that such lipase biocatalysis is very ready for industrial use, and indeed, the example above is just one of numerous examples carried out by us as well as by others. With regard to the production of fine chemicals more generally by biotransformations, an analysis has been reported of 134 such industrial processes. This reveals that on average there is a volumetric productivity of 15.5 g/L per hour and a final average product concentration of 108 g/L, figures very suitable for high economy. 

In Part I a selection of the types of membrane reactor is presented, together with chapters on the integration of membrane reactors with current industrial processes. To summarize, in Chapter 1 (Calabro) membrane bioreactors are described from an engineering point of view, together with a straightforward description and simulation, with a simple mathematical approach, of the most important configurations and processes in which they are involved. Basic principles of bioconversion, bioreactors and biocatalysis with immobilized biocatalysts are also presented. For all the cited systems the most significant parameters are defined in order to estimate their performances. The best approaches for the preparation of... 

Ionic liquids are still in the research phase. Therefore, there are only a few industrial applications known (Fig. 20.3). However, there is a large field of potentially interesting applications (Table 20.3). Several pilots or industrial processes using ILs were publicly announced. There are few reviews which describe those applications in detail [1]. Most of the potential applications are as solvents or catalysts in many chemical reactions such as Diels-Alder, Friedel-Crafts reactions, and biocatalysis. Applications in other fields such as in separations, fluid applications, and analytical applications, are lower in numbers. There are now many companies who supply ionic liquids in gram scale to multi-ton scale. Some of the key suppliers are listed in Table 20.4. In this chapter, maiifly the applications in the pilot-plant and industrial phase will be discussed. Aspects of ionic liquid stability, cost, recycling, and waste disposal will be also discussed at the end of this chapter. 

J. (2004) Applied biocatalysis for the synthesis of natural flavor compounds - current industrial processes and future prospects. Biotechnol. Lett, 26, 463-472. 

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