PHYSIOLOGICAL STATE OF ESCHERICHIA COLI AND THE INHIBITION OF DEOXYRIBONUCLEIC ACID SYNTHESIS BY PHENETHYL ALCOHOL

Abstract

The effects of concentration of phenethyl-alcohol (PEA) and the physiological state of the cells on inhibition of macromolecular synthesis in E. coli were investigated. Deoxyribonucleic-acid (DNA) synthesis by cells of E. coli from the maximal stationary phase is completely inhibited by 0.32% (v/v) PEA immediately upon addition of the inhibitor, although there is a net increase in the synthesis of ribonucleic-acid (RNA) and protein. However, DNA synthesis in cells from the exponential phase is inhibited only after an increase which corresponds to 1.4 to 1.6 times the amount of DNA present at the time of PEA addition. In a randomly dividing culture, this increment of DNA synthesis presumably represents completion of the DNA replication cycle initiated at the time of PEA addition. By programming the addition and removal of PEA, DNA synthesis can be made to pro-ceed in stepwise increments corresponding to doublings of the DNA. The data indicate that the DNA being replicated at the time of PEA addition completes the replication cycle and, although there is net synthesis of RNA and protein, no initiation of a second cycle of DNA replication occurs until the removal of the inhibitor.