FE 462 BIOCHEMICAL ENGINEERING DOWNSTREAM PROCESSING Dr Ali
FE 462 BIOCHEMICAL ENGINEERING DOWNSTREAM PROCESSING Dr. Ali Coşkun DALGIÇ
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The variables: p. H, air-flow rates, surfactants. Using lauric acid, stearyl amine t-octyl amine as surfactants, it was shown that up 90% of the cells were removed in 1 minute and 99% in 10 minutes. Page 6 6 Dr. Ali Coşkun DALGIÇ
PRECIPITATION Page 7 7 Dr. Ali Coşkun DALGIÇ
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Parameters to consider most suitable filtration equipment Page 9 9 Dr. Ali Coşkun DALGIÇ
Page 10 In some processes such as microbial biomass production, filter aids cannot be used and cell pretreatment by flocculation or heating must be considered 10 Dr. Ali Coşkun DALGIÇ
Plate and filter press most suitable for fermentation broths with a low solids content and low resistance to filtration. used as a 'polishing‘ device in breweries to filter out residual yeast cells following initial clarification by centrifugation or rotary vacuum filtration. It may also be used for collecting high value solids. Because of high labour costs and the time involved in dismantling, cleaning and reassembly, not be used when removing large quantities of worthless solids from a broth. Page 11 11 Dr. Ali Coşkun DALGIÇ
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increased temperature would lower media density but is of little practical use with fermentation broths), the diameter of the cells (could be increased by coagulation/flocculation) and the viscosity of the liquid. In practice, the cells are usually very small, of low density and are often suspended in viscous media. Page 13 13 Dr. Ali Coşkun DALGIÇ
Micro-organisms: held as discrete units in three ways. Firstly, their surfaces are negatively charged and therefore repulse each other. Secondly, hydrophilic cell walls a shell of bound water is associated with the cell which acts as a thermodynamic barrier to aggregation. Page 14 Finally, due to the irregular shapes of cell walls steric hindrance will 14 also play a part.
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Freezing and thawing of a microbial cell paste will inevitably cause ice crystals to form and their expansion followed by thawing will lead to some subsequent disruption of cells. It is slow and has not often been used as a technique on its own( used in combination with other techniques. ) ( ie α-Glucosidase from S. Cerevisiae) Page 21 21 Dr. Ali Coşkun DALGIÇ
Ultrasonication High frequency vibration (- 20 k. Hz) at the tip of an ultrasonication probe leads to cavitation, and shock waves thus produced cause cell disruption. very effective on a small scale, unsuitable for large-scale operations. Power requirements are high, there is a large heating effect so cooling is needed, the probes have a short working life and are only effective over a short range. Page 22 22 Dr. Ali Coşkun DALGIÇ
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CHROMATOGRAPHY chromatographic techniques are used to isolate and purify relatively low concentrations of metabolic products. Depending on the mechanism by which the solutes may be differentially held in a column, the techniques can be grouped as follows: (a) Adsorption chromatography. (b) Ion-exchange chromatography. (c) Gel permeation chromatography. (d) Affinity chromatography. (e) Reverse phase chromatography. (f) High performance liquid chromatography. Page 24 24 Dr. Ali Coşkun DALGIÇ
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Drying The drying of any product (including biological products) is often the last stage of a manufacturing process -spray dryer( commonly used , economic) -drum dryer -fluidized bed dryer ( common in pharmaceutical ind) -freeze dryer( suitable for heat sensitive materials) Page 30 30 Dr. Ali Coşkun DALGIÇ
Cryrstallization Page 31 31 Dr. Ali Coşkun DALGIÇ
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