The uptake byEscherichia coliand growth inhibitory properties of benzyl alcohol and phenethyl alcohol

Abstract The effects of benzyl alcohol (0–4 mg/ml) and phenethyl alcohol (0–2.5 mg/ml) on the rate of mass increase in cultures of E. coli were studied by absorbance measurements. Growth rate constants in the partially inhibited cultures were calculated. With both agents the growth rate was reduced on increasing the alcohol concentration, the extent of this reduction becoming progressively larger for equal increments in concentration. The inhibition of growth was shown to be reversible and to result from a uniform inhibition of the individual cells. The overall cellular uptake of benzyl alcohol was approximately the same as that of phenethyl alcohol. With both agents the uptake was proportional to the concentration of alcohol remaining in the medium and was independent of contact time within the range of 10–90 min. Phenethyl alcohol is, however, more effective than benzyl alcohol in inhibiting growth. This is attributed to a greater uptake of the former by the cellular membrane.