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FE 462 BIOCHEMICAL ENGINEERING

FE 462 BIOCHEMICAL ENGINEERING. DOWNSTREAM PROCESSING. The variables: pH, 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. PRECIPITATION.

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FE 462 BIOCHEMICAL ENGINEERING

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  1. FE 462 BIOCHEMICAL ENGINEERING DOWNSTREAM PROCESSING

  2. Thevariables: pH, air-flow rates, surfactants. Using lauric acid, stearyl aminet-octyl amine as surfactants, it was shown that up90% of the cells were removed in 1 minute and 99%in 10 minutes.

  3. PRECIPITATION

  4. Parameters to consider most suitable filtration equipment

  5. In some processes such as microbial biomass production, filter aids cannot be used and cell pretreatment byflocculation or heating must be considered

  6. Plate and filter press • most suitable forfermentation broths with a low solids content and lowresistance to filtration. • used as a 'polishing‘device in breweries to filter out residual yeast cellsfollowing 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.

  7. increased temperature would lower media density but is of little practical use with fermentationbroths), • the diameter of the cells (could be increased by coagulation/flocculation) and the viscosityof the liquid. • In practice, the cells are usually very small, of low density and are often suspended in viscousmedia.

  8. Micro-organisms: held as discreteunits in three ways. Firstly, their surfaces arenegatively charged and therefore repulse each other. Secondly, hydrophilic cellwalls a shell of bound water is associated with the cell which acts as a thermodynamic barrier to aggregation. Finally, due to the irregular shapes of cell walls steric hindrance will also playapart.

  9. Freezing and thawing • Freezing and thawing of a microbial cell paste willinevitably cause ice crystals to form and their expansionfollowed by thawing will lead to some subsequentdisruption of cells. • It is slow and has not often been used as atechnique on its own( used incombination with other techniques. ) (ie α-Glucosidase from S. Cerevisiae)

  10. Ultrasonication • High frequency vibration (- 20 kHz) 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-scaleoperations. • Power requirements are high, there is alarge heating effect so cooling is needed, the probeshave a short working life and are only effective over ashort range.

  11. CHROMATOGRAPHY • chromatographictechniques are used to isolate and purify relatively lowconcentrations of metabolic products. Dependingon the mechanism by which the solutes may bedifferentially held in a column, the techniques can begrouped 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.

  12. Drying • The drying of any product (including biologicalproducts) is often the last stage of a manufacturingprocess • -spray dryer( commonly used , economic) • -drum dryer- • -fluidized bed dryer ( common in pharmaceutical ind) • -freeze dryer( suitable for heat sensitive materials)

  13. Cryrstallization

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