Abstract
Deletion of the Escherichia coli K-12 chromosome associated with P2 mediated education extend through the structural gene for uridine kinase, udk, and the dcd gene encoding 2'-deoxycytidine 5'-triphosphate deaminase. The lack of uridine kinase makes a positive selection possible for these strains. Due to the dcd mutation, P2 eductants show large alterations in their deoxyribonucleoside triphosphate pools.