When Streptomyces speak in vesicles: powerful bioactive molecules encapsulated in natural nanocarriers

Extracellular membrane vesicles (eMVs) act as natural nanocarriers, facilitating microbial communication and the delivery of bioactive compounds (Liu et al., 2022). Filamentous Actinomycetota of the genus Streptomyces are renowned producers of specialized metabolites (Alam et al., 2022; Lacey & Rutledge, 2022), yet the molecular composition and functional relevance of their vesicles remain largely unexplored. In this research, we isolated and characterized the eMVs produced by two Streptomyces spp., aiming to evaluate some biological activities and to elucidate the underlying mechanisms through the analysis of their metabolomic profiles. These eMVs exhibited antibacterial activity against Gram-positive bacteria and exerted plant growth promoting effects, even under salt stress, indicating potential for stress-resilient agriculture. LC-MS-based metabolomic analysis revealed a complex assortment of primary and secondary metabolites, including molecules potentially involved in antimicrobial activity and in the modulation of plant physiology. The integration of metabolomic data with biological assays suggests that these effects may be attributable to the bioactive molecules encapsulated and delivered by the vesicles, which enhance their stability, protection, and targeted release. Overall, our findings highlight Streptomyces-derived eMVs as sophisticated natural delivery systems capable of transporting functional compounds with promising applications in sustainable agriculture and microbial biocontrol.