A new amino acid antibiotic, amiclenomycin, is produced by Streptomyces lavendulae subsp. amiclenomycini OKAMI. Its chemical structure is L-2-amino-4-(4'-amino-2',5'-cyclohexadienyl)-butyric acid. The antibiotic inhibits the growth of mycobacteria, including antibiotic-resistant strains, and this activity is reversed by biotin and desthiobiotin. α-Methyl desthiobiotin is coproduced along with amiclenomycin. In the course of searching for antimicrobial agents, amiclenomycin was discovered in culture filtrates of streptomycete strain MD580-S1, which taxonomic studies indicate is a new subspecies for which the name Streptomyces lavendulae subsp. amiclenomycini OKAMI is proposed. This paper deals with the taxonomy of the new subspecies as well as the production, isolation, characterization, structure and biological properties of amiclenomycin.