Kanamycin is an aminoglycoside antibiotic isolated from Streptomyces kanamyceticus. It is effective against gram-positive and gram-negative bacteria as well as Mycoplasma species. Kanamycin is commonly used to select for bacteria that have been transformed with a kanamycin-resistant gene and plant tissues that have the NPT II (APH3) gene incorporated in them. Kanamycin is very soluble in aqueous solution and is typically used in concentrations of 50-100 µg/ml.