Abstract
Two enzymes which phosphorylate neomycin and kanamycin have been detected in Escherichia coli strains carrying R factors. Neomycin-kanamycin phosphotransferase I can phosphorylate neomycin and kanamycin, but not butirosin. Neomycin-kanamycin phosphotransferase II can phosphorylate all three antibiotics. The enzymes also differ in their response to certain inhibitors of phosphorylation. Neomycin-kanamycin phosphotransferase II is found in certain strains of Pseudomonas aeruginosa .