There are many methods for the production of recombinant human insulin in both bacteria and yeast. One typical scheme for preparing human insulin utilizes pro-insulin that is produced in E. coli cytoplasm as an inclusion body of a fusion protein ( Chang 1998).

Manufacturing of insulin using microbes as a cell factory involves the following steps –

1. Isolation of gene: The gene for producing human insulin protein is isolated.

2. Preparation of target DNA: Circular piece of DNA called plasmid is obtained from bacteria. 3. Insertion of DNA into plasmid: The gene for insulin is inserted into the plasmid construct. The human insulin gene is now recombined with bacterial DNA.

4. Plasmid insertion: The bacterial DNA having insulin gene is inserted back into bacteria.

5. Plasmid multiplication: The bacterial cells having insulin gene are allowed to grow and multiply and during this process bacterial cells start to produce recombinant insulin. During division newly synthesized copy of cell are produced.

6. Human insulin produced by bacteria is purified.

 

Figure 7-3.2: Production of insulin by genetic engineering