Iron is essential for various metabolic and informational cellular pathways, with over 100 enzymes requiring iron-containing cofactors. Iron acquisition is crucial for microorganisms, especially pathogens, as they face strict iron homeostasis in their hosts. Direct and indirect mechanisms of iron acquisition are employed by pathogens, with the latter being more widespread and successful. Indirect iron acquisition involves the use of siderophores, small-molecule compounds that chelate ferric iron, allowing for efficient iron uptake. Siderophores can be categorized into catecholates, hydroxamates, and (α-hydroxy-)carboxylates, each forming stable complexes with Fe(III). The biosynthesis of siderophores is often catalyzed by nonribosomal peptide synthetases (NRPSs), while hydroxamate and carboxylate siderophores are synthesized through NRPS-independent pathways. Gene regulation of siderophore utilization and iron homeostasis is mediated by transcriptional and posttranscriptional mechanisms, involving proteins like Fur, DtxR, and various transcriptional regulators. The regulation of siderophore biosynthesis, secretion, and iron release is a complex process that has been extensively studied in bacteria, fungi, and plants.Iron is essential for various metabolic and informational cellular pathways, with over 100 enzymes requiring iron-containing cofactors. Iron acquisition is crucial for microorganisms, especially pathogens, as they face strict iron homeostasis in their hosts. Direct and indirect mechanisms of iron acquisition are employed by pathogens, with the latter being more widespread and successful. Indirect iron acquisition involves the use of siderophores, small-molecule compounds that chelate ferric iron, allowing for efficient iron uptake. Siderophores can be categorized into catecholates, hydroxamates, and (α-hydroxy-)carboxylates, each forming stable complexes with Fe(III). The biosynthesis of siderophores is often catalyzed by nonribosomal peptide synthetases (NRPSs), while hydroxamate and carboxylate siderophores are synthesized through NRPS-independent pathways. Gene regulation of siderophore utilization and iron homeostasis is mediated by transcriptional and posttranscriptional mechanisms, involving proteins like Fur, DtxR, and various transcriptional regulators. The regulation of siderophore biosynthesis, secretion, and iron release is a complex process that has been extensively studied in bacteria, fungi, and plants.