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.
| Advantages | Disadvantages |
|---|---|
| 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.