Microbial Dynamics and Organic Matter Cycling in Marine Environments

Marine microbial communities orchestrate the transformation and movement of organic matter across the world’s oceans, linking primary production at the surface with deep-sea reservoirs and sedimentary pools. Photoautotrophic organisms such as phytoplankton fix carbon through photosynthesis, producing organic compounds that become substrates for heterotrophic bacteria and archaea. These heterotrophs decompose detrital material, remineralise nutrients and release dissolved organic matter, thereby sustaining further microbial and higher-trophic-level activity. Viruses modulate microbial population dynamics through infection and lysis, accelerating the release of cellular contents into the dissolved pool. Physical processes—including mixing, eddy formation and particle sinking—govern the spatial distribution of organic substrates, shaping microbial community structure and function. Integrating approaches from genomics, lipidomics, metatranscriptomics and biogeochemical modelling has revealed the tight coupling between microbial metabolism and global cycles of carbon, nitrogen and phosphorus, with profound implications for climate regulation and marine ecosystem services.

Research from Nature Portfolio

Investigations of cyclonic eddies in an Eastern Boundary Upwelling System have revealed that such mesoscale features concentrate energy-rich lipids, delivering nearly ten gigagrams of lipid carbon annually to the open ocean. Lipidomic profiling showed elevated triacylglycerols and essential fatty acid-containing membrane lipids of eukaryotic phytoplankton origin within the eddy core, indicating enhanced export potential and lateral transport of organic matter.

A foundational study of open-ocean phytoplankton lipidomes demonstrated pronounced diel oscillations in triacylglycerol synthesis and consumption by eukaryotic nanophytoplankton. Daytime accumulation of energy reserves comprised up to a quarter of primary production, supporting a previously unrecognised daily carbon flux of about 2.4 Pg C yr−1. Metatranscriptomic analysis linked these lipid dynamics to haptophyte and dinoflagellate biosynthetic genes, underscoring the importance of lipid storage in global carbon budgets.

Microbial Dynamics and Organic Matter Cycling in Marine Environments publication trend

The graph below shows the total number of articles in microbial dynamics and organic matter cycling in marine environments across all publications each year (not limited to Nature Index journals).

Technical terms

Biogeochemical cycle: Natural pathways through which elements such as carbon, nitrogen and phosphorus are exchanged among living organisms, the air, water and sediments.

Mixed layer: The upper ocean layer in which temperature and salinity are relatively uniform due to wind-driven turbulence.

Lipidome: The complete suite of lipids present in a cell, community or ecosystem, reflecting metabolic state and taxonomic composition.

Triacylglycerol (TAG): An energy storage lipid composed of three fatty acids esterified to a glycerol backbone, prevalent in phytoplankton and other microbes.

Metatranscriptomics: The analysis of community-wide RNA transcripts to profile gene expression in situ, linking function to environmental conditions.

References

1. Bacterial catabolism of membrane phospholipids links marine biogeochemical cycles. Science Advances (2023).
2. Marine phytoplankton downregulate core photosynthesis and carbon storage genes upon rapid mixed layer shallowing. The ISME Journal: Multidisciplinary Journal of Microbial Ecology (2023).
3. Mixed-layer lipidomes suggest offshore transport of energy-rich and essential lipids by cyclonic eddies. Communications Earth & Environment (2025).
4. Daily changes in phytoplankton lipidomes reveal mechanisms of energy storage in the open ocean. Nature Communications (2018).