Taxonomy of actinomycetes in the deep-sea <i>Calyptogena</i> communities and characterization of the antibacterial compound produced by <i>Actinomadura</i> sp. DS-MS-114

Fifteen actinomycetes were isolated from deep-sea sediments in Calyptogena communities in the Japan Trench (depth: 5352 m) and Sagami Bay (depth: 1171 m) under incubation at 4?37 °C. A relatively large number of colonies were obtained with incubation at 30 °C from the deep-sea sediment of Sagami Bay. We found Rhodococcus, Nocardioides and Micromonospora actinomycetes in both sediments, and additionally isolated an Aeromicrobium actinomycete from the Japan Trench and Streptomyces and Actinomadura actinomycetes from Sagami Bay. Actinomadura sp. DS-MS-114 isolated from the deep-sea sediment in Sagami Bay produced an antibacterial compound against Staphylococcus aureus NBRC12732T. Structural analysis by liquid chromatography-high-resolution electrospray ionization mass spectrometry (LC-HRESIMS) and proton nuclear magnetic resonance (1H-NMR) indicated that the antibacterial compound was 5,6-dihydro-1,8-dihydroxy-3-methylbenz[a]anthracene-7,12-quinone, which is known as an immunosuppressant. The deep-sediment in the Calyptogena community may be useful as a source of various actinomycetes producing physiologically active substances.