DNA synthesis in Lactobacillus acidophilus in the absence of RNA and protein synthesis: a study with rifampicin.

Abstract

Synthesis of DNA in Lactobacillus acidophilus R-26 was investigated in the presence of rifampicin which inhibits RNA and protein synthesis. Increments in DNA of between 140 and 200% were found under these conditions. Indirect evidence is presented that these large increments are not due to the presence of several replication points in the bacterial chromosome at the time of addition of the drug. Incubation with rifampicin was found to result in a progressive decrease in the capacity for DNA synthesis. This decrease was independent of the amount of DNA synthesized during incubation with rifampicin but was dependent on the time of incubation in the presence of the drug. It is proposed that inhibition of protein and RNA synthesis in L. acidophilus does not inhibit initiation of new cycles of chromosome replication but results in a progressive loss of the capacity to replicate DNA.