[Regulation of riboflavin biosynthesis in Salmonella typhimurium]

7 independent rib genes fusions with MudJ (lacZ, Kanr) were isolated by transposon MudJ mutagenesis in Salmonella typhimurium. 5 of them are blue on the X-gal plate, and the beta-galactosidase activity of the cells grown in E medium containing various concentration of riboflavin were assayed. The results showed that the expression of rib gene are not repressed by riboflavin. It appears to be synthesized constitutively in Salmonella typhimurium.