Chemical ecology of Streptomyces-fungal interactions in soil: Competition, signaling and antifungal metabolites

Abstract

Soil is a spatially heterogeneous and chemically dynamic environment in which microorganisms often compete for spatially and temporally variable resources. Among the most ecologically important competitors are Streptomyces and filamentous fungi—two metabolically versatile groups whose interactions are strongly shaped by secondary metabolites. Although Streptomyces-derived antifungal compounds have been studied widely for pharmaceutical and biocontrol applications, their ecological and evolutionary roles in natural soil systems remain insufficiently integrated. This review synthesized Streptomyces-fungal interactions through the combined framework of chemical ecology and evolutionary competition. It examined the ecological basis of microbial antagonism in soil, the offensive chemical strategies used by Streptomyces and the defensive and adaptive responses of fungal competitors. The dual role was further highlighted of secondary metabolites as both inhibitory compounds and signaling molecules, with emphasis on how spatial heterogeneity, temporal dynamics and inducible chemistry shape interaction outcomes. Finally, the implications were considered of this eco-evolutionary perspective for biocontrol and sustainable agriculture and future directions were identified, including spatially resolved analyses, metabolic tracing and predictive modeling. Overall, antifungal metabolites in Streptomyces are best understood not as isolated bioactive products, but as context-dependent mediators of competition and communication that may contribute to adaptive diversification in soil ecosystems.