Cost effective production of siderophores by genetic manipulation for metal recovery

Secondary metabolites such as siderophores produced by microorganisms and plants bind not only Fe3+ but also commercially important elements such as Ga3+, Ge4+ and Ti4+. As numerous complexation studies suggest, siderophores are potential candidates for sustainable and environmentally friendly metal recovery technologies. However, the native and heterologous production of these siderophores is limited for many reasons, including iron inhibition, highly regulated production, the tendency to recycle siderophores and the simultaneous production of different siderophores. The most studied siderophore for metal recovery is desferrioxamine B, but since it is only produced chemically, its industrial application is limited. To solve this problem, we decided to use biological production in a natural host. In this project, we conducted experiments to optimise the media for the production of desferrioxamine B in a native host, Streptomyces pilosus, using minimal media and complex media. Streptomyces pilosus grows filamentous and therefore forms clusters mainly in minimal media, which poses a challenge for effective media optimisation. Initially, efforts were made to achieve homogeneous growth of Streptomyces pilosus, especially in minimal media without iron for desferrioxamine B production. When the growth of S. pilosus was switched from cluster to homogeneous growth, a phenotypic switch in siderophore production was observed. These studies will help to understand desferrioxamine B production in its native host. Furthermore, we look forward to optimize production of desferrioxamine in native host-Streptomyces pilosus.