Imagine you are rushed to the hospital after an injury and need an emergency blood transfusion. If there is no time to test your own blood type, the hospital may give you type O blood. This is because type O is a “universal type.” Blood types A and B each have distinct sugars attached to the red blood cells (type AB has both types of sugars), and if you receive blood with a type of sugar that your own red blood cells don’t have, your body will attack the unknown sugar and you will have a dangerous immune reaction. However, type O has no sugars and typically causes no adverse reaction, making it “universal”. Because type O is always in high demand, Stephen Withers and his team from the University of British Columbia are developing a way to turn other types of blood into type O.

Withers’ team reasoned that if you can cut off the sugars from types A, B, and AB blood, you can make type O blood. They thought perhaps creatures like mosquitos or leeches, which break down blood for their food, might have the ability to remove the A and B sugars from blood. The team compared DNA of several blood-sucking organisms specifically, looking for genes that create sugar-chopping proteins or enzymes. However, they also looked at the DNA from millions of other organisms. To look through a bunch of DNA quickly, the team used metagenomics, or the sequencing of DNA directly from the environmental rather than from pure cultures. It’s like using a net to fish, rather than a fishing rod: you’ll pick up a lot at once and not everything will be useful. But chances are high you’ll find something close to what you’re looking for and in a lot less time.

Surprisingly, the researchers found their target not in blood-sucking critters, but in humans! A bacteria that naturally lives in the human gut uses sugars from gut-wall proteins as its food source. In the lab the team found an incredibly efficient sugar-chopping enzyme within this bacteria. While early results show the enzyme is capable of converting type A to type O blood completely, it will need more extensive testing to make sure that use of the enzyme doesn’t cause any adverse side effects.

Managing correspondent: Emily Kerr

Learn More: Gut bug enzyme turns blood into type-O

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