Milbemycins, a new family of macrolide antibiotics: fermentation, isolation and physico-chemical properties.

A search for novel insecticides has yielded the milbemycins, a new family of macrolide antibiotics with insecticidal and acaricidal activity. They are produced in submerged cultures of Streptomyces hygroscopicus subsp. aureolacrimosus. Fermentation studies on the strain were conducted in shaken flasks and 30-liter jar fermentors. From the culture broth 13 milbemycins were purified to homogeneity by column and thin-layer chromatography on silica gel and alumina. Physico-chemical data, such as mass spectra, UV and IR absorption spectra, optical rotations and melting points of the milbemycins are described.