Metaproteomic insights into trace metal-dependent phosphorus utilization within North Atlantic phytoplankton communities

Oceanic phytoplankton sustain life on earth by contributing roughly half of the global net primary production. In the North Atlantic Sargasso Sea, low concentrations of the essential nutrient phosphorus (P) can limit marine microbial growth, community structure, and productivity. To cope with P scarcity, microorganisms express metal-containing hydrolytic enzymes to access the alternative pool of dissolved organic P (DOP), a process dependent on trace metal availability in the marine environment. Recently, various globally important and taxonomically widespread enzymes have emerged in ocean genomes, including diverse alkaline phosphatases and other hydrolases. However, the roles of these proteins in supporting ocean ecosystem fertility, and the relationship between P and trace metal cycling are not fully understood. To shed light on this, ambient measurements and metal-addition shipboard incubations were conducted on the 2024 BIOS-SCOPE cruise around BATS that combine in situ DOP hydrolysis rates with community metaproteomics, P pools, and trace metal concentrations. Ambient results show that DOP utilization varied greatly with mixed layer depth and microbial community composition. Incubation results demonstrated that iron (Fe), zinc (Zn), and cobalt (Co) availabilities constrained hydrolysis rates and substrate preferences. Metaproteomics provide new knowledge on the enzyme sequences involved in phytoplankton responses to nutrient stress, which is especially relevant in light of future increasing P limitation across the world’s large ocean gyres.

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Primary Presenter: Viktoria Steck, Woods Hole Oceanographic Institution (viktoria.steck@WHOI.edu)

Authors:

Catelyn Charette, Woods Hole Oceanographic Institution  (catelyn.charette@whoi.edu)

Matthew McIlvin, Woods Hole Oceanographic Institution  (mmcilvin@whoi.edu)

Mak Saito, Woods Hole Oceanographic Institution  (msaito@whoi.edu)