Type A Blood Converts to O Type with Bacterial Enzyme

On a typical day, hospitals around the United States use 17,000 liters of blood from donors. These are used in emergency surgeries, standard operations as well as your routine blood transfusion. Not everyone can take every blood type which poses a challenge especially with shortages of certain types. The interesting thing is that now scientist have observed bacteria in the human gut which produce two enzymes that can convert Type A Blood into a universally accepted type. If this research proves through peer testing and trials, it could revolutionize the way we collect blood and saves millions of lives.

“This is the first, and if such results can be repeated, it is definitely a big move forward,” says Harvey Klein, a blood transfusion specialist at the National Institutes of Health Clinical Center in Bethesda, Maryland, who was not involved in the study.


Access to efficient enzymes that can convert A and B type red blood cells to ‘universal’ donor O would greatly increase the supply of blood for transfusions. Here we report the functional metagenomic screening of the human gut microbiome for enzymes that can remove the cognate A and B type sugar antigens. Among the genes encoded in our library of 19,500 expressed fosmids bearing gut bacterial DNA, we identify an enzyme pair from the obligate anaerobe Flavonifractor plautii that work in concert to efficiently convert the A antigen to the H antigen of O type blood, via a galactosamine intermediate. The X-ray structure of the N-acetylgalactosamine deacetylase reveals the active site and mechanism of the founding member of an esterase family. The galactosaminidase expands activities within the CAZy family GH36. Their ability to completely convert A to O of the same rhesus type at very low enzyme concentrations in whole blood will simplify their incorporation into blood transfusion practice, broadening blood supply.

Nature Microbiology

“We have been particularly interested in enzymes that allow us to remove the A or B antigens from red blood cells,” Stephen Withers, Ph.D., says. “If you can remove those antigens, which are just simple sugars, then you can convert A or B to O blood.” He says scientists have pursued the idea of adjusting donated blood to a common type for a while, but they have yet to find efficient, selective enzymes that are also safe and economical but they are hopeful with finding that Type A Blood Converts with gut enzymes.

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