Prochlorococcus extracellular vesicles: molecular composition and adsorption to diverse microbes |
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| Authors: | Steven J Biller Rachel A Lundeen Laura R Hmelo Kevin W Becker Aldo A Arellano Keven Dooley Katherine R Heal Laura T Carlson Benjamin A S Van Mooy Anitra E Ingalls Sallie W Chisholm |
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| Institution: | 1. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA;2. School of Oceanography, University of Washington, Seattle, WA, USA;3. Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA |
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| Abstract: | Extracellular vesicles are small (~50–200 nm diameter) membrane-bound structures released by cells from all domains of life. While vesicles are abundant in the oceans, their functions, both for cells themselves and the emergent ecosystem, remain a mystery. To better characterize these particles – a prerequisite for determining function – we analysed the lipid, protein, and metabolite content of vesicles produced by the marine cyanobacterium Prochlorococcus. We show that Prochlorococcus exports a diverse array of cellular compounds into the surrounding seawater enclosed within discrete vesicles. Vesicles produced by two different strains contain some materials in common, but also display numerous strain-specific differences, reflecting functional complexity within vesicle populations. The vesicles contain active enzymes, indicating that they can mediate extracellular biogeochemical reactions in the ocean. We further demonstrate that vesicles from Prochlorococcus and other bacteria associate with diverse microbes including the most abundant marine bacterium, Pelagibacter. Together, our data point toward hypotheses concerning the functional roles of vesicles in marine ecosystems including, but not limited to, possibly mediating energy and nutrient transfers, catalysing extracellular biochemical reactions, and mitigating toxicity of reactive oxygen species. |
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