Isolation and characterization of a Bacillus subtilis mutant with a defective N-glycosidase activity for uracil-containing deoxyribonucleic acid.

Crude cell extracts of Bacillus subtilis 168T exhibit enzyme activity capable of releasing free uracil from phage PBS1 deoxyribonucleic acid (DNA) in the presence of ethylenediaminetetraacetate. By measuring the enzyme activity in 300 clones that emanated from mutagenized cells, we obtained a mutant strain that did not show this N-glycosidase activity. The mutant strain, designated as TKJ6901 (urg-1) exhibited no physiological abnormalities.