Microorganism, enzyme preparation, industrial

Recovery. The principal purpose of recovery is to remove nonproteinaceous material from the enzyme preparation. Enzyme yields vary, sometimes exceeding 75%. Most industrial enzymes are secreted by a microorganism, and the first recovery step is often the removal of whole cells and other particulate matter (19) by centrifugation (20) or filtration (21). In the case of ceU-bound enzymes, the harvested cells can be used as is or dismpted by physical (eg, bead mills, high pressure homogenizer) and/or chemical (eg, solvent, detergent, lysozyme [9001 -63-2] or other lytic enzyme) techniques (22). Enzymes can be extracted from dismpted microbial cells, and ground animal (trypsin) or plant (papain) material by dilute salt solutions or aqueous two-phase systems (23). 

More than 90% of enzymes are produced by fermentation by microorganisms, which are used to prepare industrial and special use enzymes. Prokaryotic cells and eukaryotic cells can be easily grown in culture, and the technology of scale-up is well established on an industrial scale. Various kinds of fungi, bacteria and yeast have been screened for the production of special enzymes. Extracellular enzymes, for instance hydrolytic enzymes, are secreted into liquid and solid culture and are relatively stable in cultivation media. 

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... 

Preparation of (S)-ibuprofen by enzyme-catalyzed enantioselective hydrolysis of racemic ibuprofen esters has been investigated by several companies such as Sepracor [50,51], Rhone-Poulenc [52,53], Gist-Brocades [54,55], and the Wisconsin Alumni Research Foundation [56]. These processes are usually performed under mild reaction conditions, yield highly optically pure product, and can be readily scaled up for industrial production. The disadvantage of these processes for (S)-ibuprofen production is the extra step needed to produce the corresponding ester of racemic ibuprofen, as well as the cost of producing the enzyme and microorganism catalysts. 

Industrial fermentations are generally more rapid and efficient when these materials are used, since they reduce the number of compounds which the cells would otherwise have to synthesize de novo . " The availability of nitrogen as well as the concentration in the media has to be considered in each case. Proteins can only be assimilated by microorganisms that secrete extracellular proteases, which enzymatically hydrolyze the proteins to amino acids. Microorganisms without this ability require protein hydrolysates, peptones, or digests composed of free amino acids prepared by hydrolyzing proteinaceous materials with acids or enzymes. 

Between 12 and IS billion US per year are spent for analytical purposes worldwide. In this sum the analytical usage of enzymes in clinical chemistry, food and cosmetic industry, and biotechnology for the routine measurement of about 80 substances, mainly low-molecular mass metabolites but also effectors, inhibitors, and the activity of enzymes themselves, is included. A wide range of immunoassays for low-molecular mass haptens, macro-molecules, and microorganisms have been made available in recent years through the enormous progress in immunological research, especially by the preparation of monoclonal antibodies. About 1 billion immunoassays are sold per year. 

Isolated Enzymes and Other Biocatalysts. As mentioned above, isolated enzymes fall under the biocatalyst domain. Purified enzymes probably will not play as large a role as microorganisms in commodity chemicals production fiom biomass, largely because of the impracticality of preparing all of the many enzymes necessary to convert glucose to a useful chemici. Purified enzymes will have an impact, however, in the pharmaceutical and fine chemicals industries, where a critical, value-added downstream step needs to be performed. 

Immobilization is the method of cultivation of microorganisms that allows a repeated use of biocatalysts (be it enzyme or whole cells), creating prerequisites for the production of valuable products in an automated continuous mode. The most considerable problem in using biocatalysts is related to mass transfer. In aerobic systems, low solubility of oxygen in carriers, especially in some gels and polymers, can decrease the effectiveness of biocatalyst action. In this respect, propionic acid bacteria, which do not require aeration, show certain advantages over aerobic cultures. At present, about eight different processes that use immobilized enzymes and cells have found industrial applications. These are mainly one-or two-step processes used in the manufacture of foods and pharmaceutical preparations (Vorobjeva et al, 1978). An essential characteristic of a biocatalyst is productivity. 

Despite the previously mentioned examples vhich clearly prove the synthetic value of BY, there are several drawbacks that limit its vhdespread application to preparative organic chemistry (i) very low substrate concentrations tolerated by the microorganism that lead to an intrinsically too low productivity (ii) difficult work-up, due to the troublesome separation of the product from a huge amount of biomass (iii) typically incomplete conversion and occurrence of side reactions that imply the use of industrially unappealing chromatographic steps (iv) presence of enzymes with the same specific biocatalytic activity that might have different enantioselectivity. 

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