Bacillus subtilis "rec assay" test with isogenic strains

Abstract

The Bacillus subtilis "rec assay" test, widely used for the detection of DNA-damaging agents, was studied in detail, using an isogenic set of strains carrying different mutations in repair or recombination functions or both. recE4 and rec-45 mutations turned out to confer on the cells the highest sensitivity to known mutagens. The recE4 strain and its isogenic rec+ strain have been tested and validated by several rec assay procedures for preferential killing by known DNA-damaging agents. The use of purified spores of the tester strains offers advantages for standardization of the assay.