Race for iron: An exploiter's perspective on siderophore-mediated networking in bacterial communities

The trace element iron is a physiological requirement of almost every living organism as it plays important roles in numerous biological processes. Nevertheless, due to the extreme low solubility of Fe³⁺ in aerobic environments, microbes need to employ sophisticated strategies to manage homeostasis of this valuable resource. One strategy is the production and secretion of Fe³⁺-complexing siderophores. Within this project, we assess competitive and cooperative strategies for the acquisition of iron through siderophores as public goods in defined microbial communities.

Corynebacterial species have been reported as frequently occurring natural siderophore exploiter in natural microbiomes, such as the nasal microbiome (1). Within this project, we investigate Corynebacterium glutamicum as model to explore the exploiter"s perspective on siderophore-mediated networking. To establish defined microbial communities, we screened for different siderophore producers allowing C. glutamicum to overcome iron-limitation. These result indicated that C. glutamicum is capable of utilizing a chemically diverse set of xenosiderophores including Escherichia coli enterobactin, Bacillus subtilis bacillibactin and Ustilago maydis ferrichrome. Adaptive laboratory evolution experiments with C. glutamicum and spent medium from different siderophore producers resulted in the isolation of C. glutamicum strains with superior xenosiderophore utilization capabilities. Establishment of synthetic co-cultures grown in microfluidic devices confirmed the dependency of C. glutamicum on enterobactin production of E. coli under iron limiting conditions. With this set-ups we are able to examine the impact of iron management strategies on the structure and dynamics of microbial communities, uncovering spatial variations and dynamics.

(1) Zhao et al. (2024): The ISME Journal.