Improvement of the strain for the rapid identification of genes encoding restriction and modification enzymes.

The E. coli AP1-200-9 strain for rapid identification of genes encoding restriction and modification enzymes carries a temperature sensitive lacZ gene fused to the damage-inducible dinD locus. A derivative of this strain was constructed that has a wild-type form of this locus which allows for a more efficient identification of recombinant plasmids encoding restriction and modifications enzymes.