Some effects of chloramphenicol on the metabolism of chlorella

Summary A chloramphenicol concentration of 3 mg per ml inhibits uptake of ¹⁴C-labelled phenylalanine, lysine, and adenine by Chlorella cells. Incorporation into both the free pool and the TCA insoluble fraction is inhibited. The inhibition is not related to inhibition of protein synthesis since cycloheximide (a specific inhibitor of protein synthesis in Chlorella) does not inhibit uptake of the ¹⁴C-labelled amino acids. Uptake of ¹⁴C-uracil is not inhibited by chloramphenicol.Both chloramphenicol and 2.4-dinitrophenol stimulate endogenous respiration of Chlorella, but whereas the latter reduces the internal concentration of ATP, the former (in concentrations of 1–3 mg/ml) stimulates it about two-fold. Similar concentrations of chloramphenicol decreases slightly the concentration of ADP, and it is therefore suggested that in Chlorella, chloramphenicol concentrations of 1–3 mg per ml inhibit some energy-linked reactions by preventing ATP utilization.