Fermentation liquid clarification

The first step following fermentation is the separation of solids from the liquid growth media, a step generally referred to as cell separation. More specifically, when the desired products are contained within the cells (intracellular) this step is called cell harvesting and when the products are extracellular it is known as broth clarification. The list of antibiotics with their producer organisms, molecular weight, and whether they are extracellular or intracellular is shown in Table 14.6. 

Initial liquid cultures in, e.g., 500-mL shake flasks can provide a sufficient volume of fermentation broth for the generation of growth and production profiles and for preliminary isolation experiments relating to clarification, stability, solvent solubility, and affinity for chromatographic resins. 

The clarification process is the unit operation designed to separate the cells from the liquid broth immediately after the fermentation. The most commonly used techniques are filtration and centrifugation. When the product is inside the cells, cell disraption is necessary after the clarification. Intracellular products make the purification process of biomolecules more complex compared to extracellular compounds. After the cell dismption, there is an increase in viscosity of the medium due to the release of nucleotides and the desired compound is delivered together with all other molecules, requiring additional steps for its purification. ... 

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