Blood Changing Bacteria

Blood. It can be gruesome, but it is essential for survival. In the UK alone, we need 6,000 people to donate blood every day to meet the demand, and 200,000 new donors every year to replace those who can no longer donate. Could a new enzyme found in our gut be the answer to blood shortage?

The following image can be found on the NHS Give Blood website, and details the blood stock levels in the UK for the week commencing 13th Aug 2018.


The image explains that the NHS aim to have 6 days stock of each blood type to meet demand across the country. However, this target is rarely met and the demand for blood donations is constant. Currently, they are appealing for O- blood type donations, as stocks may fall below 2 days supply in the coming weeks. Currently, the GiveBlood campaign is especially in need of blood donations from minority backgrounds, particularly black and South Asian ethnic minorities. Let’s get some background on blood: what are the different types, why can’t we have any old blood, and why do we need to keep donating?

Blood comes in 4 main groups: O, A, B, and AB. Your blood type depends on the genes you inherit from your parents. On the surface of red blood cells are combinations of proteins and sugars called antigens which, along with the antibodies (i.e. the body’s natural defence) found in your plasma, determine your blood type.

Here is a table which helps find blood type:


Antigens on 
red cell

in plasma


none anti-A & anti-B


A anti-B


AB A and B


blood type-2If you were to give a person with type A blood, a transfusion of type B blood, their body would see it as a foreign substance and reject it. The person with type A blood has antibodies which dislike type B antigens. Type AB blood can receive blood from anyone as they don’t have antibodies which fight off other blood types. Type O can donate to everyone (i.e. the universal red cell) as they have no antigens to reject BUT, they cannot accept from anyone other than type O as they have both A and B antibodies. The last point to consider is whether your blood type is positive (+) or negative (-) (i.e. the Rhesus System), but this is something we’ll discuss in another post.

Blood doesn’t last forever. It cannot be stored infinitely. When you donate you aren’t just giving blood, you’re providing the variety of components in blood: red and white blood cells, platelets and plasma. All of these can be given separately to a patient dependent on what they require at the time. Red blood cells can be stored for up to 35 days, platelets for up to 7 days, and plasma for up to 3 years. Therefore, we continually need to donate to replace the blood used and that which cannot be stored any longer. Red blood cells have haemoglobin, which enables oxygen to be carried around the body and these are given to people with a low haemoglobin concentration (e.g. sickle cell diseases, cancer patients etc.). Platelets help blood clot by clumping together to stop bleeding after injury. These can, for example, be used for patients after transplant or chemotherapy procedures. Lastly, plasma is the fluid which carries all the blood cells and components, as well as a number of other substances such as albumin (i.e. a protein useful for treating kidney and liver disease), clotting factors (i.e. treats diseases where blood does not clot properly), and immunoglobins (i.e. help to fight infection). All of these factors can play vital roles, so your donated blood could help more than one person. With such a demand for blood, and fewer people donating, what is science doing to help blood shortages?

Researchers at the University of British Columbia, Canada, have used an enzyme created by bacteria found in the human gut, to change type A blood into type O. This is not a new discovery, Stephen Withers and his group have been working on this technique since they discovered an enzyme able to perform such a task back in 1982. changing blood typeHowever, the announcement made in August was in relation to a new enzyme which is more powerful, and efficient than the previous one. So how does it change blood type? As stated before, blood type is determined, in part, by the antigens on the blood cell surface. This enzyme is able to strip a blood cell of it’s antigens, leaving it blank, and therefore creating type O blood. This enzyme has been shown to work quickly and on a whole blood donation, not just a sample. Therefore this could mean quick, and safe, blood changing procedures in emergencies, when other blood types are not available (as type O is a universal donor).

As the Global population increases, and natural disasters occur more, the demand for blood donations will only increase. A discovery such as this, where you can change blood type to become a universal donor, could ease future pressures on the system which is already overstretched, and see the survival of more people in need.

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