Enzymes from gut bacteria can turn any blood type into universal Type O blood.

The human ABO blood group system is defined by specific sugar antigens on the surface of red blood cells. Type A has N-acetylgalactosamine, Type B has galactose, and Type AB has both, while Type O lacks these specific markers. In 2019, researchers from the University of British Columbia led by Stephen Withers identified a powerful pair of enzymes from the gut bacterium Flavonifractor plautii.These enzymes work together to convert A-type blood into O-type blood by removing the offending sugar molecules. The gut was a logical place to look for such enzymes because the lining of the digestive tract contains mucins, which are proteins heavily decorated with similar sugar structures. Bacteria in the gut have evolved to produce these enzymes to break down mucins for energy.The research team utilized a technique called functional metagenomics to screen DNA from human gut microbes. They discovered that the enzymes GalNAc deacetylase and galactosaminidase were 30 times more efficient at stripping antigens than previously studied candidates. This breakthrough could significantly alleviate blood shortages by allowing hospitals to convert surplus A or B blood into the universal O-negative type.While the technology is promising, clinical trials are necessary to ensure that the enzymatic process is 100% efficient. Even a small amount of remaining sugar antigens could trigger a life-threatening immune response in a recipient. Current research is focusing on ensuring the enzymes leave the red blood cells fully intact and functional for transfusion purposes.