[Operon for riboflavin synthesis in Bacillus subtilis. XI. Determination of the type of regulation using a test for dominance of operator-constitutive and regulator-constitutive mutations].

The strain GSY 468 of Bacillus subtilis, giving persistent unstable merozogotes was used as recipient in transformation. Diploid cells bearing a regulator constitutive or operator constitutive mutation were obtained, and their phenotype was studied. The operator constitutive mutation behaves as a dominant one, but the regulator constitutive is recessive. Hence the regulation type in riboflavin operon is negative. The product of the regulator gene is obviously a repressor protein.