Inhibition of DNA synthesis and cell division in Salmonella typhimurium by azide.

Evidence has been obtained that sodium azide is an inhibitor of cell division in wild-type and aziA strains of Salmonella typhimurium. The bacteria grown in media containing sodium azide and glucose formed long filaments. It has been found that sodium azide had a stronger inhibitory effect on DNA synthesis than on cell mass increase. When filaments produced by azide action were transferred to azide-free medium very rapid increase in DNA content was observed during the first 45 min. After this time, when relative DNA content was increased the rate of DNA synthesis was reduced and cell divisions reappeared. Inhibitory effect of azide on DNA biosynthesis in vitro was observed with toluenized cells of S typhimurium. Only ATP-dependent radioactive dTMP incorporation into DNA was affected by sodium azide. It had no effect on the incorporation in the absence of ATP. Mutant aziC was isolated in S. typhimurium by scoring for clones with normal cell division in the presence of sodium azide. Azide had much less effect on DNA biosynthesis in vivo and in vitro in aziC cells as compared with isogenic controls.