Annual dynamics and metagenomics of marine vesicles: One more layer of complexity in the dissolved organic fraction

Abstract Despite the role of extracellular vesicles (EVs) in genetic and biogeochemical exchange in the ocean, there is a notable dearth of studies delving into the seasonal annual dynamics of EVs in uncultured microbial communities. Here, quantitative data from the oligotrophic Mediterranean Sea revealed that EVs mL −1 ranged from 10 4 to 10 6 throughout the year and correlated with microbial abundances (correlation coefficient = 0.67). The ratio of EVs per cell ranged from 1 to 4. Vesicle metagenomics identified copiotrophic and oligotrophic prokaryotic species, such as Flavobacterium and Pelagibacter , putatively dominating the production of EVs containing DNA in the annual dataset. Micromonas spp. and others Mamiellophyceae emerged as the dominant eukaryotic producers of EVs containing DNA. Genes belonging to viruses were consistently identified in purified vesicles. The relative proportion of viral contigs found in the vesicle fraction (2.4–30.4%) suggested that the release of viral genomes in EVs could be more common than previously thought.