The riboflavin kinase encoding gene ribR of Bacillus subtilis is a part of a 10 kb operon, which is negatively regulated by the yrzC gene product.

The riboflavin kinase encoding gene ribR is situated within a 12 genes locus ytmI-ytnM of the Bacillus subtilis chromosome. Here we demonstrate that ribR is transcribed as part of a 10 kb ytmI-ytnM operon. The riboflavin overproduction phenotype of B.