Inhibition of sporulation by DNA gyrase inhibitors

The effects of oxolinic acid and novobiocin - which respectively inhibit the A and B subunits of DNA gyrase, and therefore inhibit DNA synthesis - have examined in sporulating cultures of Bacillus subtilis. Although both inhibitors prevent sporulation, this is not due to inhibition of DNA synthesis. Instead, they affect protein synthesis generally, though weakly, but have very marked effects on the formation of individual enzymes. These effects are reproducible, but the type of enzyme that will be affected is not predictable. The results point to an involvement of DNA gyrase in the transcription of some genes. This is suggested as the reason for the effect of the inhibitors on spore formation, which they block mainly at Stage O-I.