The effect of phenethyl alcohol on Bacillus subtilis transformation : I. Characterization of the effect

Abstract

Phenethyl alcohol at a concentration of 0.05 % reduces neither the growth rate of Bacillus subtilis, as determined by A 630 m μ measurements, nor the viable titer during a 60-min exposure. When 0.05 % phenethyl alcohol is added concomitantly with DNA to competent B. subtilis, there is a 50–70 % inhibition of transformation without any effect on the viable titer of the cells. Treatment of isolated transforming DNA with 0.5 % phenethyl alcohol is without any effect on the specific biological activity, and no evidence for binding or interaction of [ 14C]phenethyl alcohol and DNA was obtained by Sephadex chromatography, methylated albumin kieselguhr chromatography, or CsCl density gradient centrifugation. Addition of phenethyl alcohol after the uptake of DNA was completed did not inhibit transformation, and the potential transformants became resistant to deoxyribonuclease and phenethyl alcohol inhibition at the same time. Incubation of competent cells with phenethyl alcohol prior to the addition of DNA resulted in a greater inhibition of transformation than when phenethyl alcohol was added simultaneously with DNA, and if this incubation was over an hour long, removal of the phenethyl alcohol by centrifugation and washing did not restore competence. Addition of more competent cells resulted in more transformants, but addition of an excess of DNA failed to change the number of transformants obtained from an inhibited mixture. Phenethyl alcohol inhibits the transport of radioactive DNA but not the initial attachment of DNA to competent cells.