Downstream process steps in intra cellular enzymes production
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Enzymes are universally present in living organisms; each cell synthesizes a large number of different enzymes to maintain its metabolic reactions. The choice of procedures for enzyme purification depends on their location. On the one hand, isolation of intracellular enzymes often involves the separation of complex biological mixtures. On the other hand, extracellular enzymes are generally released into the medium with only a few other components. Downstream processing is a very important step in biotechnology because costs for collection, concentration and purification of the final product are significant. High product concentrations in the supernatant or inside the cells and efficient purification are therefore important aspects in the overall economy of enzyme manufacture. The degree of purity of commercial enzymes ranges from raw enzymes to highly purified forms and depends on the application. Often enzymes may be purified several hundred-fold but the yield of the enzyme may be very poor, frequently below 10% of the activity of the original material. In contrast, industrial enzymes will be purified as little as possible, only other enzymes and material likely to interfere with the process which the enzyme is to catalyze, will be removed. Unnecessary purification will be avoided as each additional stage is costly in terms of equipment, manpower and loss of enzyme activity. As a result, some commercial enzyme preparations consist essentially of concentrated fermentation broth, plus additives to stabilize the enzyme's activity. At the industrial level, the strategies used for the purification should be inexpensive, rapid, high-yielding and amenable to large-scale operations. They should have the potential for continuous product recovery, with a relatively high capacity and selectivity for the desired product. The extent of purification varies with the order of the purification steps; and this aspect has been evaluated through different purification protocols pursued by various investigators. Enzymes are applied in various areas of application, the most important ones are technical use, manufacturing of food and feedstuff, cosmetics, medicinal products and as tools for research and development. Enzymatic processes - usually carried out under mild conditions - are often replacing steps in traditional chemical processes which were carried out under harsh industrial environments (temperature, pressures, pH, and chemicals).