By which species Human Insulin is commercially produced?

Question

Accepted Answer

The correct option is 1: Escherichia

The correct species used for the large-scale commercial production of human insulin, known as 'Humulin,' is **Escherichia**, specifically the bacterium *Escherichia coli* (*E. coli*). This process is a classic example of successful genetic engineering using recombinant DNA technology. The human gene coding for insulin is chemically synthesized and inserted into a small, circular piece of DNA called a plasmid, which is then introduced into the *E. coli* host cell. *E. coli* is the microorganism of choice because it grows extremely rapidly, doubling its population in about 20 minutes, making it ideal for the quick, high-volume production needed in industrial fermentation tanks. Furthermore, its genetic makeup is thoroughly understood, and it is easily manipulated, allowing scientists to create modified strains that efficiently produce and secrete the human protein, which can then be harvested and purified for use by diabetic patients.

The incorrect option is 2:
**Clostridium** is incorrect because species in this genus, such as *C. botulinum* and *C. difficile*, are primarily known as human pathogens. These bacteria are obligate anaerobes, meaning they can only grow in the absence of oxygen, and they form highly resistant spores. Culturing them on an industrial scale would require highly specialized, expensive anaerobic facilities, which is impractical for mass production. More importantly, many *Clostridium* species produce potent toxins, which poses a severe risk of contamination for a therapeutic product intended for human injection.

The incorrect option is 3:
**Rhizobium** is incorrect because its primary function is not related to recombinant protein production. *Rhizobium* is a soil bacterium famous for its role in agriculture, where it forms a symbiotic relationship with legume plants (like peas and beans) by creating root nodules to fix atmospheric nitrogen. This highly specialized, symbiotic metabolism and slower growth rate are not conducive to the rapid, high-yield fermentation required for commercial pharmaceutical production. Its use as an industrial host would be complex, inefficient, and expensive compared to a non-symbiotic, fast-growing microbe like *E. coli*.

The incorrect option is 4:
**Mycobacterium** is incorrect, largely due to practical and safety concerns. This genus includes major human pathogens, such as *Mycobacterium tuberculosis*. Unlike *E. coli*, mycobacteria have a complex, waxy cell wall that makes them difficult to lyse and extract proteins from. Crucially, they are very slow-growing, with generation times measured in hours or even days, which drastically reduces the yield and significantly increases the cost and time required for large-scale commercial manufacturing, making them an economically unfeasible choice for routine insulin production.