Cell Separation and Disruption, Product Recovery, and Purification

Abstract

Advances in upstream production (in the bioreactor) have been successful in promoting high product titres, and downstream processing now is important to obtain the final biological product in its desired purity and concentration level. Downstream processing of a biological product consists of multiple steps of individual physicochemical operations. These operations are integrated into a sequence to yield an optimal product recovery scheme. Downstream processing of a biological product that is produced via fermentation process, in general, starts with cell separation step and is followed by cell disruption operation and, finally, product recovery and purification. All the major elements of relevant technologies are presented in this chapter. After fermentation process, the target product has to be separated from the depleted fermentation broth containing microorganism cells, fermentation ingredients remained, and metabolic waste products generated along the fermentation process. For an extracellular product, a solid-liquid separation operation can be applied directly just after fermentation process to acquire a product-rich suspension. These separation processes might involve filtration and centrifugation steps, which are detailed in this chapter. On the other hand, for a product of interest that is synthesized intracellularly by the producing host cell and is not secreted to surrounding medium, it is necessary to harvest the cells first and subsequently release the target product from the cell compartments by external physical force and/or chemical treatment. Several classical cellular lysis procedures are available and are practically applied for a wide range of biological products. The cell disruption techniques are reviewed in this chapter. After the cells are broken open, the target product is released to surrounding medium. The product-rich suspension is then processed to remove cell debris in order to prepare an extract that is free of cell or cell debris for further product recovery and purification processes.