Decoding interactions in a soil microbiome Streptomyces community through multi-omics: functional insights into siderophore ecology
Background Streptomyces are key contributors to soil microbiome function, known for their biosynthetic diversity. While advances in -omics technologies have improved our understanding of microbiome composition and metabolic potential, the mechanisms underpinning interspecies interactions remain poorly resolved. Here, we investigate the molecular basis of interactions among four sympatric Streptomyces soil microbiome isolates, focusing on phenotypic, metabolomic and transcriptomic responses. Results Co-culture experiments revealed that one isolate, strain A, exhibited pronounced phenotypic changes when grown alongside each of the other three strains. Untargeted metabolomics and RNA-seq analyses showed that strain A undergoes distinct metabolic and transcriptional shifts depending on its partner, with the strongest response elicited by strain C. Despite all four strains possessing a conserved desferrioxamine biosynthetic gene cluster, only strain C constitutively produced desferrioxamine B (DFO-B), a hydroxymate siderophore, indicating a role of iron bioavailability in the interaction. Supplementation with DFO-B or iron mimicked the growth stimulation of strain A observed in co-culture with strain C, and CRISPR base editing of desD in strain C abolished both DFO production and the phenotypic induction of strain A. However, transcriptomic profiles of strain A varied significantly depending on the partner strain, with distinct sets of biosynthetic gene clusters and metabolic pathways activated in response to strains B and C, suggesting additional cues beyond DFO-B. In contrast, strain D did not elicit growth stimulation in its partners, and itself showed downregulation of amino acid and carbon metabolism when co-cultured with strain C. These findings indicate that Streptomyces interactions are not only mediated by siderophore piracy but also involve complex, strain-specific molecular responses. Conclusions Our findings demonstrate that Streptomyces interactions are highly strain-specific and only partly mediated by siderophore piracy, with DFO-B acting as a potent interspecies cue. The divergent molecular responses to different partners suggest nuanced mechanisms of microbial sensing and competition. These insights advance our understanding of microbial crosstalk and highlight the ecological and evolutionary complexity of siderophore-mediated interactions. By integrating transcriptomics, metabolomics, and biochemical assays, we present a robust framework for dissecting microbial interactions, with implications for microbiome engineering and synthetic community design. Overall design: RNA-seq profiling for 4 Streptomyces spp. Isolated from soil. Samples were collected considering axenic and co-culturing experiments in petri dishes at 3 data points (day 2, day 3 and day 4). Each sample contains a mixuture of the extracted RNA of the 4 isolates.