Newly discovered enzymes allow for blood types A, B, and AB to be converted to type O, the universal donor type. Converting various blood types to type O could increase the blood supply and improve safety.
The process employs two bacterial glycosidase gene families that produce enzymes capable of removing the A and B antigens. As an added benefit, the process occurs at neutral pH and doesn't require large amounts of enzymes, a problem with earlier attempts to convert blood types.
Source: Liu QP, et al., Bacterial glycosidases for the production of universal red blood cells, Nature Biotechnology, published online ahead of print April 1, 2007.