Isolation and characterization of delftibactin A, a non-ribosomal peptide with broad antimicrobial activity

Siderophores are relatively small compounds secreted by many bacteria and are able to chelate various metal ions thereby increasing their bioavailability. Deftibactin A, a molecule belonging to this class of compounds, is a non-ribosomal peptide (NRP) able to convert gold ions, which are toxic to the microorganism growing in a gold-rich environments, into gold nanoclusters. It was recently discovered that filtered supernatants recovered from the growth media of Delftia sp., possess a broad spectrum antimicrobial activity. In order to isolate and characterize active substances, an efficient RP-HPLC-DAD method was developed. Coupled with LC-MS-MS and NMR structural information, identity of Delftibactin A as the major active substance was positively confirmed. Our chromatographic method also permitted to study temperature dependence of Deftibactin A production as well as yields and metabolite distributions in various Delftia spp. isolates.