The ocean absorbs about 30% of anthropogenic CO2. A major sequestration process is through photosynthesis to transform CO2 to organic matter by marine phytoplankton. The process is called biological pump. The supply of bioavailable nitrogen is one of key factors driving the pump as bioavailable nitrogen is a major limiting nutrient for phytoplankton growth in the ocean. Producing new bioavailable nitrogen, N2 fixation is thus a critical process influencing CO2 sequestration in the ocean. However, our understanding on the environmental factors regulating N2 fixation in the ocean is limited.

Applying multidisciplinary approaches, Dr. Tung-Yuan Ho’s group from Research Center for Environmental Changes demonstrated that sufficient Ni supply and NiSOD (Ni superoxide dismutase) expression is essential for a major marine diazotroph, Trichodesmium, to reduce oxidative stress generated during photosynthesis and thus protects its N2 fixation process under high light conditions. The findings explain why Trichodesmium can carry out N2 fixation and photosynthesis simultaneously and survive and bloom in the surface water of the tropical ocean. The results may also shed light on the mechanisms of photoinhibition for phytoplankton under high solar radiation conditions.

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Core lab used: Academia Sinica Protein Clinic (ASPC)

Nickel may protect marine nitrogen fixation and enhance blue carbon sequestration