Isolation and identification of siderophores produced by cyanobacteria

Cyanobacteria are one of the most successful and oldest forms of life that are present on Earth. They are prokaryotic photoautotrophic microorganisms that colonize so diverse environments as soil, seawater, and freshwater, but also stones, plants, or extreme habitats such as snow and ice as well as hot springs. This diversity in the type of environment they live in requires a successful adaptation to completely different conditions. For this reason, cyanobacteria form a wide range of different secondary metabolites. In particular, the cyanobacteria living in both freshwater and sea produce many metabolites that have biological activity. In this review, we focus on metabolites called siderophores, which are low molecular weight chemical compounds specifically binding iron ions. They have a relatively low molecular weight and are produced by bacteria and also by fungi. The main role of siderophores is to obtain iron from the environment and to create a soluble complex available to microbial cells. Siderophores play an important role in microbial ecology; for example, in agriculture they support the growth of many plants and increase their production by increasing the availability of Fe in plants. The aim of this review is to demonstrate the modern use of physico-chemical methods for the detection of siderophores in cyanobacteria and the use of these methods for the detection and characterization of the siderophore-producing microorganisms. Using high-performance liquid chromatography-mass spectrometry (LC-MS), it is possible not only to discover new chemical structures but also to identify potential interactions between microorganisms. Based on tandem mass spectrometry (MS/MS) analyses, previous siderophore knowledge can be used to interpret MS/MS data to examine both known and new siderophores.