Streptomyces spp. are well-known producers of secondary metabolites with diverse biological activities. We screened the substances that regulate polyp-to-jellyfish transition, called strobilation, of the moon jellyfish ( Aurelia coerulea ) from the Streptomyces culture library. Among the culture extracts of the strains tested, Streptomyces albus HUT6047 inhibited the strobilation of A. coerulea . The active component in strain...