Microbial communities ubiquitously inhabit diverse global ecosystems and play an important role in numerous biological processes. Social interactions such as intra- and inter-species communication have a strong influence on the composition and behaviour of these communities. In this context, the exchange of various secondary metabolites plays a central role. Notably, siderophores are an important class among these metabolites. In response to iron limitation, most bacteria secrete siderophores that exhibit high affinities to Fe³⁺. The iron-siderophore complexes can subsequently be taken up by the microbes via specific receptors. Pyoverdine (PVD), a fluorescent siderophore produced by various Pseudomonas species, is known to be involved in several types of social interactions^1,2. While PVD-based interactions have been extensively studied^3,4,5, the importance of the spatial and temporal distribution of these processes and their impact on community composition and development remain largely unexplored. To analyze the dynamics of PVD-mediated intra- and interspecies interactions, we aimed to develop Pseudomonas putida strains where PVD production can be controlled gradually and non-invasively by light. To achieve this goal, we employed the optogenetic two-component systems (TCS), Dusk⁶ and REDusk⁷, in P. putida to regulate the expression of the pfrI gene encoding an alternative sigma factor, which is essential for PVD production in P. putida. We could demonstrate that the biosynthesis of PVD can be specifically, gradually, and dynamically controlled in these strains at the single-cell level by modulating the conditions for illumination. This optogenetic approach thus enables the dynamic transition from PVD producers to non-producers and even to over-producers, thereby allowing a detailed analysis of spatial and temporal aspects of PVD-mediated intra- and interspecies communication.

¹ Kramer et al., Nat Rev Microbiol, 2020

²Ghssein et al., Biology, 2022

³Becker et al., Sci Rep, 2018

⁴Rayi et al., ACS Chemical Biology, 2024

⁵Mridha et al., Commun Biol, 2022

⁶Ohlendorf et al., J Mol Biol., 2012

⁷Multamäki et al., ACS Synthetic Biology, 2022