Enzyme sources industrial enzymes

Until about 1950, the predominant method of producing industrial enzymes was by extraction from animal or plant sources by 1993, this accounts for less than 10%. With the exception of trypsin, chymosin, papain [9001 -73-2J, and a few others, industrial enzymes are now produced by microorganisms grown in aqueous suspension in large vessels, ie, by fermentation (qv). A smaH (5%) fraction is obtained by surface culture, ie, soHd-state fermentation, of microorganisms (13). 

Sources of Proteinases. More than 80 per cent of all industrial enzymes are hydrolytic in action and most are used for the depolymerization of natural substances. Almost 60 per cent of these enzymes are proteolytic, and used by the detergent, dairy and leather industries. 

The greatest variety of industrial enzymes are presently derived from microbial sources, with a lesser diversity coming from plant and animal sources 34), Enzymes derived from plant sources and which are used extensively in the food industry include papain, bromelain, ficin, and amylases. Animal enzymes of economic importance include trypsins, lipases, and gastric proteases. 

Bacteria represent a promising source for the production of industrial enzymes. Bacterial cellulases are an especialfy interesting case in point. Many thermophilic bacterial species produce cellulases that are stable and active at high temperature, resistant to proteolytic attack, and stable to mechanical and chemical denaturation. However, cellulase productivities in bacteria are notoriously low compared to other microbial sources. In this paper bacterial enzyme production systems will be discussed with a focus on comparisons of the productivities of known bacterial cellulase producers. In an attempt to draw conclusions concerning the regulation of cellulase synthesis in bacterial systems, a tentative model for regulation in Acidothennus cellulofyticus has been developed. 

Table 3.1 Projected sales of industrial enzymes by application ( US millions) for the US. Source Amvir Associates (adapted from Wrotnowski, 1997).

In the traditional brewing process, malt both acts as a raw material (starch and protein source) and as an enzyme source. Improved process economics and reliability may be obtained by replacing part of the malt with industrial enzymes and umnalted grains such as barley. 

Starch derived from maize, potatoes, barley, cassava or other somces must be pretreated with hydrolytic enzymes (amylases, amyloglucosidase, proteases), which carry out liquefaction, saccharification and protein hydrolysis, respectively, before it can be fermented by yeasts and other microorganisms into potable or non-potable alcohol. Enzymes can be added in the form of malt (germinated barley) or koji (germinated rice), but this is expensive. Therefore, industrial enzymes have nearly totally replaced malt and koji as enzyme sources, thereby not only improving the economics but also the predictability of the process. 

Mcroorgamsms - piSINFECTANTSAND ANTISEPTICS] (Vol 8) - [ANALYTICALMETHODS - TRENDS] (Vol 2) - controlof [INDUSTRIAL ANTIMICROBIAL AGENTS] (Vol 14) -as corrosive agents [CORROSION AND CORROSION CONTROL] (Vol 7) -in cosmetics [COSMETICS] (Vol 7) -H2 production from [HYDROGEN] (Vol 13) -industrial enzymes from pNZYME APPLICATIONS - INDUSTRIAL] (Vol 9) -nonconventnonal food sources [FOODS, NONCONVENTIONAL] (Vol 11)... 

F. Niehaus, C. Bertoldo, M. Kahler, and G. Anthranikian, Extremophiles as a source of novel enzymes for industrial application, Appl. Microbiol. Biotechnol. 

Other plants such as potatoes, cauliflower, cherries, and soybeans and several fungi may also be used as sources of peroxidase enzymes. Soybeans, in particular, may represent a valuable source of peroxidase because the enzyme is found in the seed coat, which is a waste product from soybean-based industries [90]. In this case, it may be possible to use the solid waste from the soybean industry to treat the wastewaters of various chemical industries. In fact, the direct use of raw soybean hulls to accomplish the removal of phenol and 2-chlorophenol has been demonstrated [105]. However, it should be noted that this type of approach would result in an increase in the amount of solid residues that must be disposed following treatment. Peroxidases extracted from tomato and water hyacinth plants were also used to polymerize phenolic substrates [106], Actual plant roots were also used for in vivo experiments of pollutant removal. The peroxidases studied accomplished good removal of the test substrate guaiacol and the plant roots precipitated the phenolic pollutants at the roots surface. It was suggested that plant roots be used as natural immobilized enzyme systems to remove phenolic compounds from aquatic systems and soils. The direct use of plant material as an enzyme source represents a very interesting alternative to the use of purified enzymes due to its potentially lower cost. However, further studies are needed to confirm the feasibility of such a process. 

Major biotechnological uses of the biomass carbohydrate moiety have attracted worldwide attention. Controlled cellulose degradation by cellulases may produce materials for important multifarious applications carbohydrates that can be used in the food and beverage industries, cellulose microfibril fragments for non-caloric food additives, hyperabsorbent cellulose fibers from fragmented cellulose microfibrils which can be used in biomedical, commercial and house-hold absorbent materials. Biomass-derived glucose syrups can also be used as carbon source in industrial fermentations for the production of antibiotics, industrial enzymes, amino-acids, and bulk chemicals. 

Proteolytic enzymes are by far the most important of the commercially available industrial enzymes. These enzymes, being essential parts of the metabolic system of most living organisms, can be isolated from innumerable sources. 

Source. Enzymes for food applications come from all three kingdoms plant, animal, and microbial. Traditionally used plant and animal enzymes are the plant proteases such as papain, ficin and bromelain, plant amylases from malt, and animal rennin which is used in cheese manufacture. Microbial cells are the usual and most promising future source of industrial enzymes. Estimates of the number of microorganisms in the world tested as potential sources of enzymes fall around 2% with only about 25 organisms, including a dozen or so fungi, currently used for industrial enzymes. 

Some of the traditionally used industrial enzymes (e.g., rennet and papain) are prepared from animal and plant sources. Recent developments in industrial enzyme production have emphasized the microbial enzymes (Frost 1986). Microbial enzymes are very heat stable and have a broader pH optimum. Most of these enzymes are made by submerged cultivation of highly developed strains of microorganisms. Developments in... 

Figure 10-22 Methods of Immobilizing Enzymes. Source From H.H. Weetall, Immobilized Enzymes and Their Application in the Food and Beverage Industry, Process Biochem., Vol. 10, pp. 3-6, 1975.

Almost 3200 different enzymes have been listed and categorized by the International Union of Biochemistry and Molecular Biology in its last report in 1992. An encyclopaedic description of more than 7000 commercially available enzymes can be found in Ref [36]. Table 10.2 collects some industrial enzymes suppliers. Enzymes exhibiting the same catalytic function are known as homologous enzymes and they fall into two classes heteroenzymes and isoenzymes. The first group includes enzymes derived from different sources but which catalyse identical reactions, yet show different chemical and kinetic characteristics. A comprehensive enzyme information system, termed BRENDA, is available via the Internet (http //www.brenda.uni-koeln.de). 

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