If you google “E. coli”, you’ll quickly see that this bacterium has a bad reputation. The first results are related to infections and food safety issues. However, if you ask scientists, you will find that they fall no short when praising its advantages. It is one of the model organisms most widely used in synthetic biology. We have talked before about E. coli, but today we wanted to go over five extremely useful public health applications of this bacterium
We start with a classic, the production of a key molecule that enables us to process glucose: insulin. Back in 1980, scientists managed to modify these bacteria to mass-produce this important molecule for our metabolism. Up until then, people with diabetes were given insulin from animal origin, but this method of manufacturing had its disadvantages: the peak of insulin occurs 3 or 4 hours after the injections, and diseases like Transmissible Spongiform Encephalopathy (TSE) have made difficult to use raw animal tissues for manufacturing. By using E. coli, the process became safer and more efficient. Nowadays most of the insulin in the world comes from two microorganisms: our beloved E. coli and the yeast S. cerevisiae.
Schistosoma mansoni is a parasite that infects 200 million people worldwide and causes symptoms like high fever, abdominal fluid retention and hypertension. The disease is especially relevant in developing areas like Sub-Saharan Africa, where it kills thousands of people every year. Detecting the infection is usually done by microscopic inspection of the patient’s stool, to detect the parasite’s eggs. However, a team of researchers at Imperial College seems to have found a different approach. By modifying E.coli, they are able to detect a molecule released by the infecting parasite during its larval stage: elastase. At present, they’re trying to develop the method further, so medical doctors in developing areas can have a diagnostic test without having to move the samples through a cold chain.
Boosting the immune system against cancer
Melanoma is the most aggressive type of skin cancer. It can also extend to different parts of the body, in a process called metastasis. When the melanoma is in an advanced stage or has become metastatic, the treatment must be systemic — meaning that the response against cancer has to be through the whole body. Interleukins are a group of proteins made by cells in our immune system. In particular, Interleukin-2 is made by the T cells and it is at the vanguard of the immune system response against melanoma.
By providing additional doses of interleukin, doctors try to boost the patient’s immune system, so it fights the cancerous cells. Back in the 80s, researchers developed a way of making E. coli produce Interleukin-2, making this molecule available at industrial quantities.
Making our body to grow
We humans go from measuring about 50 cm in height when we are new-borns to reaching heights of 180 cm when we become adults. Somatotropin is the name of one key molecule behind this growth. That’s why this hormone is also called the human growth hormone, although it is also responsible for other tasks: keeping our muscular mass and strength, reducing fat deposits and improving the absorption of proteins. When the body is not able to produce it in enough quantities, it can cause short height, low blood sugar, decreased muscle mass, high cholesterol levels, or poor bone density.
Luckily, this hormone is available commercially for therapeutic treatment. And all thanks to E.coli. Using the bacteria for manufacturing came also with additional advantages. Up until then, the hormone was extracted from donated human pituitaries. And it came with a problem: the growth hormone obtained this way was not pure, but a mixture of pure hormone and modified ones, that played a role in physiological roles other than growth. Switching the production to E. coli, the researchers were able to produce more hormone in a safer way.
Stopping the bleeding
Haemophilia is an inherited bleeding disorder in which the blood doesn’t clot properly. This can lead to spontaneous bleeding as well as bleeding after injuries or surgery. If you look closer at the blood composition of people who suffer from haemophilia, you will find that the most usual cases ha lower levels of two types of molecules. These molecules are called clotting factors VIII and IX. Using E. coli as their model organism, a team of researchers is looking into how to make the bacteria produce one of the clotting factors.
These examples are only a few, and they are centred around treating diseases. However, E. coli is widely used in many different industries: cosmetics, biotechnology, food… Overall, industrial uses of E. coli contribute over $500 billion to the global economy.
So, the next time you see a report on the news about E. coli infecting people or being at the center of a food safety discussion… don’t forget that it has also saved thousands of lives worldwide, thanks to the help of genetic engineering and synthetic biology.