E.coli is one of the most widely used and well-studied expression systems. This system is excellent for expression of functional non-glycosylated proteins, since the production of glycosylated proteins require a Golgi apparatus, which E. coli cells do not posses. Bacteria did not develop a sophisticated mechanism for performing posttranslational modifications. The following table summarizes the advantages and disadvantages of E.coli as an expression system.
|Rapid expression||Protein with disulfide bonds is difficult to express|
|High yield||Produces unglycosylated proteins|
|Ease of culture and genome modification||Protein produced with endotoxin|
|Inexpensive||Acetate formation resulting in cell toxicity|
|Mass production is fast and cost-effective||Protein produced as inactive inclusion bodies that require refolding|
Figure 1. Bacteria expression system.