<jats:title>Abstract</jats:title><jats:p>A new antibacterial cyclic peptide, named curacomycin (<jats:bold>1</jats:bold>), and its analogue dechlorocuracomycin (<jats:bold>2</jats:bold>) were isolated from <jats:italic>Streptomyces curacoi</jats:italic> (NBRC 12761<jats:sup>T</jats:sup>) and <jats:italic>Streptomyces noursei</jats:italic> (NBRC 15452<jats:sup>T</jats:sup>), respectively, by using genome mining. The chemical structures of these two peptides were determined by using a combination of MS (ESI) and NMR spectroscopy. The structure of compound <jats:bold>1</jats:bold> was determined to be a cyclic peptide that consisted of six amino acids, including: valine (Val), leucine (Leu), isoleucine (Ile), ornithine (Orn), β‐hydroxyasparagine (OHAsn), and 5‐chlorotryptophan (ClTrp). The NMR data of compound <jats:bold>2</jats:bold> were very similar to that of compound <jats:bold>1</jats:bold>, which indicated that the structure of compound <jats:bold>2</jats:bold> was a dechlorinated analogue of compound <jats:bold>1</jats:bold>. A comparison of the antimicrobial activities of these two peptides indicated that the presence of chlorine in compound <jats:bold>1</jats:bold> was critical for its antimicrobial activity. The proposed biosynthetic gene clusters for compounds <jats:bold>1</jats:bold> and <jats:bold>2</jats:bold> were found in the genome data of <jats:italic>S. curacoi</jats:italic> and <jats:italic>S. noursei</jats:italic>, respectively. The functions of the biosynthetic genes were considered by comparison of the two gene clusters.