Chloramphenicol acetylation in Streptomyces

Twenty-one strains of actinomycetes were screened for the presence of chloramphenicol acetyltransferase, the enzyme responsible for chloramphenicol resistance in many species of bacteria. Only five strains, belonging to three species, yielded mycelial lysates which catalysed the formation of chloramphenicol acetates in the presence of acetyl-coenzyme A: Streptomyces coelicolor Müller, S. acrimycini, and S. griseus. A mutant of S. acrimycini selected for an increase in resistance to chloramphenicol had a higher specific activity for chloramphenicol acetyltransferase than that found in the parental strain; the enzyme was not inducible in the mutant, the parental strain, or any other strain tested. Chloramphenicol was not acetylated by lysates of a strain of S. venezuelae, the organism known to produce it.