A new antibiotic, P-3355, was produced in the culture broth of a new Streptomyces sp., S. amylovorus. The taxonomy of S. amylovorus and the isolation, biological and physicocochemical properties, and chemical structure of the antibiotic P-3355 are discussed. The structure was (5S, 6S)-6-amino-1-formyl-5-hydroxyl-1,3-cyclohexadiene.