Biological products can be extracellular (e.g., alcohols, acids, amino acids, antibiotics, enzymes), intracellular (e.g., recombinant DNA products) or periplasmic (e.g., recombinant DNA products). If the bioproduct including enzymes or metabolites remains inside the micro-organism then it has to be broken down to recover the products of interest. Also in many cases the amount of extracellular product secreted by the micro-organism when compared to the amount stored inside may be much less. Intracellular
products including recombinant proteins are produced as inclusion body. Then it is prudent to destroy the cell wall to recover the entire product. Generally, intracellular product recovery is expensive. Several additional unit operations are required as shown in Figure 3.1 to recover intracelluar products.