An oceanographic sampler, known as a rosette, during a 2013 cruise in the North Pacific. Each bottle contains water from different depths, which is how researchers collected samples of the vitamins at sea.
Kevin Simans/University of Washington
An oceanographic sampler, known as a rosette, during a 2013 cruise in the North Pacific. Each bottle contains water from different depths, which is how researchers collected samples of the vitamins at sea.

All animals, from humans to whales to sea cucumbers, need vitamin B-12. But only certain microbes can make the complex, cobalt-containing molecule. For land dwellers a main source is the microbes that thrive in animals’ guts, which is why beef is such a good source of B-12. Shellfish also accumulate a lot of B-12.

In the oceans, the source of their vitamins for some marine organisms is sometimes mysterious. In the surface waters of the open oceans, a main supplier of B-12 was believed to have been cyanobacteria.

But University of Washington oceanographers have now found that vitamin B-12 exists in two distinct versions in the oceans — regular B-12 and pseudo B-12, which turns out to be more common in seawater. The study has implications for where algae and other organisms can get a vitamin that is essential to fueling marine life. The paper is in the Jan. 10 issue of the Proceedings of the National Academy of Sciences.

“I think the world is getting used to the idea that all lifeforms are in some ways dependent on microorganisms,” said corresponding author Anitra Ingalls, a UW associate professor of oceanography at the College of the Environment. “This is another case where microorganisms are playing a really big role in the survival of others, but not quite in the way that we had expected.”

 

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