In the course of our screening for new antibiotics, we have discovered factumycin (antibiotic, A40A), a unique antibiotic belonging to the aurodox (X-5108), kirromycin, efrotomycin, mocimycin, heneicomycin (A21A) group. Factumycin is found in the culture broth of Streptomyces lavendulae, designated ATCC 31312 (MA4758 in the Merck & Co., Inc., Culture Collection) and is active in vitro vs. both Gram-positive and Gram-negative organisms. In addition, factumycin can be used as a growth-permitting agent for animals.