On a daily basis hospitals in the US burn through about 35,000 pints of donated blood for emergency surgeries, operations, and routine transfusions. But not just any blood will do. The patient and donor blood types need to be compatible.

"Now, researchers analyzing bacteria in the human gut have discovered that microbes there produce two enzymes that can convert the common type A into a more universally accepted type. If the process pans out, blood specialists suggest it could revolutionize blood donation and transfusion."

"People typically have one of four blood types—A, B, AB, or O—defined by unusual sugar molecules on the surfaces of their red blood cells. If a person with type A receives type B blood, or vice versa, these molecules, called blood antigens, can cause the immune system to mount a deadly attack on the red blood cells. But type O cells lack these antigens, making it possible to transfuse that blood type into anyone. That makes this “universal” blood especially important in emergency rooms, where nurses and doctors may not have time to determine an accident victim’s blood type."

If the research holds up the availability of "universal" donor blood could double.