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Essential Vitamins in the Marine Environment

Emily Smail, a doctoral candidate in the USC College marine environmental biology program, stands near a water sampling system on the deck of the research vessel Kilo Moana near Hawaii. Photo credit Eric Webb.
Emily Smail, a doctoral candidate in the USC College marine environmental biology program, stands near a water sampling system on the deck of the research vessel Kilo Moana near Hawaii. Photo credit Eric Webb.

Two USC College biologists have received support from the National Science Foundation to examine the conditions that lead to the synthesis of B vitamins in the marine environment and the influence of those vitamins on marine life.

The principal investigator on the project is Sergio Sañudo-Wilhelmy, a professor of biological sciences and earth sciences. Eric Webb, an assistant professor of biological sciences, is the co-principal investigator.

Many forms of life depend on B vitamins for metabolism at the cellular level, and some organisms synthesize B vitamins themselves. The rest have to find a way to eat or absorb B vitamins to survive, and these “outside sources” of B vitamins are essential to microscopic organisms that have a central role in the functioning of ocean ecosystems.

“Many fundamental metabolic pathways — for example, DNA synthesis and the fixation of carbon dioxide — require B vitamins,” Sañudo-Wilhelmy said. “Some organisms, mostly bacteria, can make B vitamins, but everything else, including human beings, needs to get them from the environment, from food or water.”

Sañudo-Wilhelmy and Webb will examine the influence of B vitamins on forms of marine phytoplankton that include bacteria capable of photosynthesis and organisms known as eukaryotes. These microscopic organisms are responsible for a process of global importance — they convert carbon dioxide at the ocean surface into organic matter that can settle to the ocean floor and trap carbon there for decades or longer.

Although B vitamins are critical to marine ecosystems, their origins are poorly understood. The project will try to identify the different types of bacteria and single-celled microorganisms that synthesize B vitamins and release them into the water. The project also will identify the nutrients and trace metals that are needed for this synthesis to occur.

Iron and cobalt are critical. The synthesis of vitamin B7 requires iron, and the synthesis of vitamin B12 requires cobalt, but Sañudo-Wilhelmy said there’s a hitch.

“The two elements with the lowest concentration in the ocean are cobalt and iron,” he said.

B vitamins occur in seawater at extraordinarily low levels — so low that they are measured in parts per trillion. Sañudo-Wilhelmy said the project will develop protocols for measuring B vitamins at these low levels in the open ocean.

Sañudo-Wilhelmy and Webb work in the USC College marine environmental biology program and as faculty members of the USC Wrigley Institute for Environmental Studies.

Working with them are Emily Smail, a doctoral candidate in the USC College marine environmental biology program, and Lynda Cutter, a research lab specialist.