In multicellular systems, the major communication and transport strategies, used inside and between cells, is the secretion of extracellular vesicles (EVs) thus we hypothesize that EVs play a major role also in marine unicellular communities. Several physiological roles have been proposed for EVs in marine environment, including excretion, cellular communication, gene transfer, phage resistance, toxicity, carbon cycling and actually it is well known that vesicles can contain DNA, RNA, protein and polypeptides. The isolation and characterization of EVs represents a technological challenge not fully solved; despite several protocols have been proposed it is still not clear what is the best method, moreover there are no protocol dedicated to marine eukaryotes. For these reasons, our first aim was to establish an efficient protocol of EVs isolation. We used a model organism already cultured in our lab: Alexandrium minutum (from now on A. minutum). A. minutum is a dinoflagellate that blooms regularly along the Catalan coast and it is of particular interest since this specie can produce toxins dangerous for human health; it is important to highlight that based on numerous evidences in prokaryotes, it has been suggested that the overwhelming majority of toxin released from cells is encapsulated in EVs. Picture of the isolated vesicles were done with cryo-TEM (Transmission Electron Cryo-microscopy) which is the only way to visualize the bilayers lipid membrane characteristic of vesicles; moreover, this method allowed EVs to keep the round-shape. At environmental level, thanks to several datasets of sequenced marine microbial communities publicly available (e.g. Tara Ocean metatranscriptomes), we were able to detect genes markers for EVs production and release (e.g. Rab family, SNARE), identify their different taxonomy and visualize the importance of EVs production at global level

16 Symposium of Aquatic Microbial Ecology (SAME16), “From Boat to Bench”- Integrating field observation with lab experiments, 1-6 September 2019, Potsdam, Germany.-- 1 page

Peer Reviewed