We describe the unprecedented formation of six ansamitocin derivatives that are deoxygenated at C-7 of the ansamitocin core. The ansamitocin core is obtained by fermentation experiments that employ a variety of Actinosynnema pretiosum mutants and mutasynthetic approaches. The video shows in detail how the mutasynthetic experiments are conducted. Additionally, the antiproliferative test of the new ansamitocin derivatives is shown.