A putative siderophore locus was detected in the genome of the violacein-producing bacterium Massilia sp. NR 4-1 and predicted to direct the biosynthesis of a molecule that is structurally related to the thiazoline-containing siderophore micacocidin. In order to track this compound, we analyzed the metabolic profiles of Massilia cultures grown under different iron concentrations. A compound which was found to be predominantly produced under iron deficiency was subsequently isolated. Its structural characterization by spectroscopic and bioinformatic analyses revealed a previously not known diastereomer of the cytotoxic alkaloid agrochelin. The structure of this natural product, which was named massiliachelin, corresponds to the assembly line encoded by the identified siderophore locus.

Bacteria of the genus Massilia represent an underexplored source of bioactive natural products. Here, we report the discovery of massinidine (1), a guanidine alkaloid with antiplasmodial activity, from these microbes. The unusual scaffold of massinidine is shown to originate from L-phenylalanine, acetate, and Larginine. Massinidine biosynthesis genes were identified in the native producer and validated through heterologous expression in Myxococcus xanthus. Bioinformatic analyses indicate that the potential for massinidine biosynthesis is distributed in various proteobacteria.