Kanamycin (also known as kanamycin A) is an aminoglycoside bacteriocidal antibiotic, available in oral, intravenous, and intramuscular forms, and used to treat a wide variety of infections. Kanamycin is isolated from the bacterium Streptomyces kanamyceticus and its most commonly used form is kanamycin sulfate. Kanamycin is used in molecular biology as a selective agent most commonly to isolate bacteria (e.g., E. coli) which have taken up genes (e.g., of plasmids) coupled to a gene coding for kanamycin resistance (primarily Neomycin phosphotransferase II [NPT II/Neo]). Bacteria that have been transformed with a plasmid containing the kanamycin resistance gene are plated on kanamycin (50-100 μg/mL) containing agar plates or are grown in media containing kanamycin (50-100 μg/mL). Only the bacteria that have successfully taken up the kanamycin resistance gene become resistant and will grow under these conditions. As a powder kanamycin is white to off-white and is soluble in water (50 mg/mL). Mammalian cells and other eukaryotes are screened using G418, a similar aminoglycoside antibiotic, which KanMX confers resistance against. At least one such gene, Atwbc19 is native to a plant species, of comparatively large size and its coded protein acts in a manner which decreases the possibility of horizontal gene transfer from the plant to bacteria, it may be incapable of giving resistance to kanamycin to bacteria even if gene transfer occurs.Synonyms: Kanamycin A, Kantrex