Streptomyces verticillus is a species of Gram-positive bacteria in the genus Streptomyces. Whilst screening fermentation broths of this species for bioactivity in the early 1960s, Hamao Umezawa and colleagues at the Institute of Microbial Chemistry in Tokyo identified a family of glycopeptide antitumor antibiotics called the bleomycins. Examples of the bleomycins in clinical use include bleomycin A<sub>2</sub> (also known as bleomycin) and bleomycin A<sub>5</sub> (also known as pingyangmycin). Both are used to treat lymphomas (e.g. Hodgkin's lymphoma), head and neck cancer, and testicular cancer.