![]() The degree of resolution will mainly depend on the similarities to the metabolite of other molecules present in the concentrate, and the degree of purity required in the final product. The earlier steps will have achieved variable degrees of purification which may determine the degree of resolution necessary during the purification step. The final step in the recovery of a product is purification which aims at obtaining the product in highly purified state. The products are recovered from such resins by solvent (organic) extraction, changed pH etc. These resins may be apolar (e.g., styrene-divinyl bcneze), polar (e.g., sulfoxide, amide etc.), or semipolar (e.g., acrylic ester). The porosity of the resin determines the surface available for adsorption. Most compounds are adsorbed to the resins in non-nonized state. These are porous polymers without ionization. The product is recovered from the ion exchangers by ion displacement this also regenerates the ion exchanger. Some antibiotics are recovered directly from the whole broth using ion exchange resins. Liquid ion exchangers dissolve only in non-aqueous solvent carrier and the separation is similar to liquid-liquid extraction. (ii) They may be added to the extract and removed by decantation. Solid ion exchangers may be used in two ways: These may be solid, e.g., dextran, cellulose, polyamine, acrylate etc., or liquid, e.g., a solvent carrying a functional group like phosphoric acid mono- or diester etc. These are polymers having firmly attached ionizable groups (anions or cations) which ionize under a suitable environment. The method of cell disruption must not damage the product of interest the suitability of the methods is usually assessed in terms of recovery of a cellular enzyme activity following cell disruption: Generally, cell disruption is achieved by mechanical means, lysis or drying. Disintegration of Cells :ĭisruption of microbial cells is usually difficult due to their small size, strong cell wall and high osmotic pressure inside cells. Flocculation and floatation are used for the most efficient recovery of microbial biomass in some single cell protein production systems. The cells collected in the foam are readily recovered. In any case the gas bubbles absorb to and surround the cells, raising them to the surface of medium in form of foam (floatation) long chain fatty acids or amines promote stable foam formation. In cases, where flocculation is not effective, very fine gas bubbles can be created by sparging, release of overpressure or electrolysis. Since sedimentation rate of a particle increases with size, flocculated cells can be recovered by centrifugation. Flocculation, i.e., sticking together of cells, can be induced by inorganic salts, mineral hydro-colloids and organic polyelectrolytes. Small bacterial cells, which are difficult to separate even by centrifugation, can be recovered as follows. In addition, equipment cost, power consumption, temperature etc. But difficulties arise due to small differences in the densities of the particles and the medium. It may be used to separate bacteria and usually protein precipitates. ![]()
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