Effects of Phenylethyl Alcohol on Chlorella pyrenoidosa

Asynchronous as well as synchronous cultures were used to study the effect of phenylethyl alcohol on Chlorella pyrenoidosa. The following observations were made:

• 1 Autotrophic growth and the synthesis of DNA and chlorophyll were inhibited more than 80% by 8.4 mM phenylethyl alcohol when added to synchronous suspensions containing autospores.
• 2 Autospore formation did not occur when fully grown cells capable of division were transferred to 4.2 mM phenylethyl alcohol.
• 3 Photosynthetic oxygen evolution of asynchronous cultures was inhibited more than 70 % by 21 mM phenylethyl alcohol.
• 4 Endogenous respiration in the dark was stimulated by 8.4 mM, while higher concentrations were inhibitory.
• 5 Glucose respiration in the dark was inhibited by all concentrations in the range from 8.4 mM to 21 mM. Assimilation of glucose in darkness was retarded by phenylethyl alcohol at concentrations which gave maximal stimulation of endogenous respiration.

It is concluded that phenylethyl alcohol is not a specific inhibitor of DNA synthesis. The prime effect appears to be on respiration and photosynthesis.