MALDI imaging mass spectrometry of fresh water cyanobacteria: Spatial distribution of toxins and other metabolites

Cyanobacteria are among the most ancient forms of life, yet they are known to synthesize highly sophisticated defense molecules, such as the highly hepatotoxic cyclic peptides microcystins and nodularins produced by the genera Microcystis, Anabaena and Nodularia. These metabolites are released by cyanobacteria to water environments causing episodes of fatalities among animals and humans. To better understand the releasing of these metabolites, imaging mass spectrometry (IMS) using matrix-Assisted laser desorption ionization-Time of flight (MALDI-TOF) was herein applied to determine the spatial distribution of such toxins directly on agar-based cultures. Other key metabolites such as aeruginosin 602 and the siderophore anachelin were also mapped in mixed cyanobacterial cultures, showing the great potential of IMS to spatially monitor the biochemical details of cyanobacterial defense and interactions.