Race for Iron: Controlling siderophore production in P. putida via RGB & UV-light

Microbial communities are an essential component of various global ecosystems and participate in crucial biological processes. The complex social interactions, characterized by intra- and interspecies communication, significantly influence community behavior and composition. In this context, the exchange of various secondary metabolites plays a central role. Notably, siderophores are an important class among these metabolites, due to their central role in microbial iron acquisition. Pyoverdine (PVD), a fluorescent siderophore produced by various Pseudomonas species, exemplifies this by mediating vital social interactions and serving as a virulence factor in the infection process of Pseudomonas aeruginosa and other pathogenic Pseudomonads. Furthermore, PVD is becoming increasingly important for different biotechnological applications such as plant growth promotion and soil bioremediation.

Despite the depth of research on PVD-related interactions, the spatial and temporal dynamics governing these processes are still poorly understood. To this end, we developed and applied different optogenetic strategies to precisely control PVD synthesis in Pseudomonas putida non-invasively and with high spatiotemporal resolution. To achieve this goal, we implemented light-responsive two-component systems and caged-compounds as optogenetic switches for the control of PVD biosynthesis in P. putida. This approach allowed a dynamic transition from PVD production to non-production states, and even to overproduction, thereby facilitating detailed analysis of how siderophore-mediated interactions influence community composition over time and space. The reprogrammability of bacterial social behavior was demonstrated by modulating light exposure/intensity conditions of RGB and UV-light to fine-tune PVD synthesis.

The optogenetic switches will thus enable precise control over cellular behavior, offering insights into intra- and inter-species microbial cooperation, competition, and resilience. This approach can thus deepen our understanding of the ecological and pathogenic roles of siderophores and will provide new insights into community dynamics and pathogen-host interactions.