Superoxide dismutase shapes manganese stoichiometry in Southern Ocean diatoms.

In Southern Ocean diatoms from an Antarctic polynya, superoxide dismutases account for ~0.7 micromoles Mn per moles of carbon and ~20% of total cellular Mn.

• Why it matters: Biomass elemental ratios in marine phytoplankton are important for primary production projections, yet the molecular mechanisms linking metal availability to stoichiometry are often unclear.
• What they did: The study combined metaproteomics, Bayesian modeling, and geochemical measurements to estimate superoxide dismutase contributions to Mn:C, then used polar diatom culture proteomes to test metal limitation effects.
• The result: Mn limitation is linked to depletion of Mn superoxide dismutases and a concurrent increase in nickel superoxide dismutase, enabling molecular parameterization of ecosystem-scale models.

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