The bacteriostatic action of captan: alterations of RNA metabolism in E. coli

The growth of E. coli in broth cultures was inhibited in a concentration dependent manner by the addition of captan. Treated cells showed no evidence of lysis and maintained a viable character. Following a single exposure to 500 microM captan, cells exhibited a lag period of approximately six hr and then grew to maximum density. During the period of arrested growth, captan apparently inhibited the synthesis of RNA as measured by the incorporation of tritiated uridine into acid-insoluble material. This apparent inhibition was due in part to a captan mediated decrease in the uptake of uridine from the media into the soluble nucleotide pool. By means of RNA isolation, polyacrylamide gel electrophoresis, and RNA quantitation, it was demonstrated that captan caused a selective loss of large (16 and 23 S) ribosomal RNA's. However, cellular concentrations of transfer RNA and 5S ribosomal RNA were unaffected by captan treatment.