Petrobactin is a bis-catechol siderophore found in M. hydrocarbonoclasticus, A. macleodii, and the anthrax-producing B. anthracis. Like other siderophores petrobactin is a highly specific iron(III) transport ligand, contributing to the marine microbial uptake of environmental iron.
The iron-chelated petrobactin complex readily undergoes a photolytic oxidative decarboxylation due to its α-hydroxy carboxylate group, converting iron(III) to the more biologically useful iron(II).