Enzymes process design

Kohler, N., Lonchamp, D. and Thery, M. (1985) Injectivity improvement of xanthan gums by enzymes process design and performance evaluation. SPE 13587, Proceedings of the SPE International Symposium on Oilfield and Geothermal Chemistry, Phoenix, AZ, 9-11 April 1985. 

One of the issues of the industrial process design is related to the heat released by this reaction. A temperature rise will decrease the acetic acid yield, not only because the equilibrium constant becomes lower (the reaction is exothermic see section 2.9) but also because it will reduce the enzyme activity. It is therefore important to keep the reaction temperature within a certain range, for instance, by using a heat exchanger. However, to design this device we need to know the reaction enthalpy under the experimental conditions, and this quantity cannot be easily found in the chemical literature. 

Mitochondria produce energy through a process called oxidative phosphorylation. This process uses oxygen and simple sugars to create adenosine triphosphate (ATP), the cell s main energy source. A set of enzyme complexes, designated as complexes I-V, carry out oxidative phosphorylation within mitochondria. 

It is also important to note that molecular biology, while it is a very powerful tool, is probably most effective in industrial process development when used in conjunction with other techniques such as enzyme formulation, immobilization and appropriate process design engineering. ... 

Figure 8 is a schematic flow diagram for the hydrolysis of waste newsprint. Most of the process design criteria and the economic evaluations of the saccharification process have been based on newsprint as substrate. Notable analyses are those of Wilke and co-workers (21) and Humphrey (22). In the hydrolysis, the substrate is first pretreated (milling), to make it more accessible to the enzyme. Saccharification takes place in a reaction vessel, where the substrate is contacted with the enzyme solution from the fermentation vessel. Glucose solution is separated from unreacted substrate at the outlet of the vessel and the solution passes on to a concentration stage before the sugar is used in the yeast fermentation to produce alcohol. 

Very many technical and commercial factors are important such as the utility of the product (cost-benefit relationships), ease of scale-up, the productivity of the process etc. Process design, for instance, involves a series of choices, such as the use of isolated enzyme or intact microorganism, use of free or immobilised cell or enzyme, use of mutant or genetically modified cell, or batch or continuous processing etc. Such choices depend on other factors such as the availability and cost of precursors, product purity required, intended scale of operation and existing skills and equipment available within the Organisation. 

As in the case of enzymes, whole cells can be immobilized for several advantages over traditional cultivation techniques. By immobilizing the cells, process design can be simplified since cells attached to large particles or on surfaces are easily separated from product stream. This ensures continuous fermenter operation without the danger of cell washout. Immobilization can also provide conditions conducive to cell differentiation and cell-to-cell communication, thereby encouraging production of high yields of secondary metabolites. Immobilization can protect cells and thereby decrease problems related to shear forces. 

With both methods, the amount of enzyme added is compared to the amount of product produced ([P] = % [S]) to obtain a measure of the operating stability. At the beginning of a process design the prices for a unit of enzyme as well as for a mole (or pound or kilo or ton) of product are known, so an assessment of the influence of catalyst cost is possible. 

Design of Enzyme Processes High-Fructose Corn Syrup (HFCS)... 

In designing a microbial conversion process many important aspects require careful consideration, for example, the selection of a compound to be synthesized, a survey of available substrates, and the routes or reactions needed. Another point (the most important one) is to find microbial enzymes which are suitable for the processes designed, and to subsequently evaluate the enzyme s potential. Moreover, the discovery of a new enzyme or a new reaction provides a clue for designing a new microbial transformation process. To find microbial enzymes that are suitable as potent catalysts, the capabilities of well-known enzymes or reactions need to be reassessed, and novel microbial strains or enzymes need to be discovered. Screening may be one of the most efficient and successful ways of searching for new or suitable microbial enzymes. 

To understand the potential of pressure application to enzyme processes and to help elucidate the reaction mechanism as well as a rational design of alcoholysis reactors for future scale-up, we investigated the influence of temperature, pressure, exposure times, and decompression rates on the activity of a commercial immobilized lipase (Novozym 435) activity in high-pressure C02 medium. 

Cosio IG, Fisher RA, Carroad PA. Bioconversion of shellfish chitin waste waste pretreatment, enzyme production, process design and economic analysis. J Food Sci 1982 47 901-905. 

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