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Marine microbes shed packets of DNA, nutrients

Bacterial vesicles may offer genetic exchange opportunities, affect carbon cycle

BACTERIA BUBBLE  Photosynthetic bacteria called Prochlorococcus pinch off bits of themselves to make sacs called vesicles (one indicated by arrow). The vesicles may influence carbon levels in the ocean and affect climate change.

Superabundant bacteria in the ocean routinely sacrifice parts of themselves, scientists have discovered. This sacrifice, in which bacteria pinch off minuscule spheres called vesicles, may influence climate change by affecting how much carbon dioxide the ocean can absorb.

Photosynthetic bacteria in the genus Prochlorococcus shed two to five vesicles a day, researchers led by biological oceanographer Sallie Chisholm of MIT report in the Jan. 10 Science. Each vesicle is a membrane-wrapped bubble with about one-sixth the diameter of the bacteria and is packed with lipids, proteins, RNA and even DNA. Together, the hordes of bacteria may cast off 10,000 to 100,000 metric tons of organic carbon into the ocean each day in these parcels, Chisholm’s team calculates.

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