Deep-sea Streptomyces spp. as a source of bioactive secondary metabolites and new siderophores

The phylum Actinomycetota is predominantly responsible for producing the majority of marine microbial secondary metabolites of which the genus Streptomyces is the most prolific, biosynthesizing most of the well-known clinically useful antibiotics and other bioactive compounds, including siderophores that scavenge iron from the environment. Some well-known Streptomyces -derived siderophores, studied within the EU’s Horizon2020 SECRETed project, have biomedical and environmental applications. In continuation of our previous studies on the genus Streptomyces [ 1 ] [ 2 ] , in the present study, emphasis was given on the discovery of novel siderophores. Novel approaches such as computational mass spectrometry and molecular networking (MN) were applied with the purpose of exploring the chemical profile of the extracts and identifying related analogues. Liquid culture supernatants of three Streptomyces strains were selected due to their siderophore content ( S. coelicoflavus , S. tritolerans and S. sclerotialus ) and screened for their secondary metabolites. The crude extracts were subjected to chromatography techniques for the separation of the molecules. Standard TLC was conducted for an initial screening using different reagents, including FeCl3 for siderophore detection. For the structural elucidation of the isolated compounds, 1- and 2-D Nuclear Magnetic Resonance (NMR) spectroscopy and Mass Spectrometry (MS) were employed. In order to obtain pure compounds, High Performance Liquid Chromatography (HPLC) and Preparative Thin Layer Chromatography (PTLC) were used. Overall, fifteen compounds were isolated and identified : one cyclic hydroxamic acid siderophore, two diketopiperazines, five a-pyranones, one tyramine alkaloid, three benzoic acid derivatives, one benzodioxole derivative, one purine nucleoside and one novel madurastatin analogue. Acknowledgement European Unionʼs Horizon2020 Research and Innovation Programme (Grant Agreement No. 101000794). Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany