The marine bacterium Pseudoalteromonas sp. S2B, isolated from the Gulf of Mexico after the Deepwater Horizon oil spill, was found to produce lystabactins A, B, and C (1-3), three new siderophores. The structures were elucidated through mass spectrometry, amino acid analysis, and NMR. The lystabactins are composed of serine (Ser), asparagine (Asn), two formylated/hydroxylated ornithines (FOHOrn), dihydroxy benzoic acid (Dhb), and a very unusual nonproteinogenic amino acid, 4,8-diamino-3-hydroxyoctanoic acid (LySta). The iron-binding properties of the compounds were investigated through a spectrophotometric competition.