Abstract
SUMMARY: Chloramphenicol was found to inhibit the growth of Pythium ultimum, showing a maximum dose-response at a concentration of 100 μg./ml. Mycelium grown in the presence of chloramphenicol 100 μg./ml., was devoid of the mitochondrial cytochromes aa3 and b but contained increased cytoplasmic cytochrome c. Mitochondria in thin sections of hyphae grown in the presence of chloramphenicol resembled mitochondria in normal hyphae. In negatively stained preparations of isolated normal mitochondria stalked particles were observed on the cristae. These particles could not be demonstrated in mitochondria from hyphae grown in the presence of chloramphenicol 100 μg./ml.