Many marine cyanobacteria and heterotrophic bacteria have been shown to produce siderophores. The majority of the pelagic marine siderophores that have been structurally characterized contain α-hydroxy acid moieties, either in the form of citrate or β-hydroxy-aspartate that participate in iron(III) binding. Marine microbial production of suites of amphiphilic siderophores differing in the fatty acid appendage is intriguing. The membrane affinity, surface activity, and physical characteristics of these siderophores suggest that variations in amphiphilic character within the suites of the marinobactins, aquachelins, and amphibactins confer important physiological functions. Very few of the hundreds of structurally characterized siderophores are amphiphilic. Known terrestrial or pathogenic amphiphilic siderophores include the ornibactins. Structural characterization of siderophores produced by marine bacteria and investigations of iron acquisition processes employed by these bacteria has been initiated only relatively. Microbial lipopeptides comprise a class of biomolecules produced by microorganisms to modify the immediate environment. Lipopeptides and related compounds are known to interact with surfaces and to modify microbial activities.