Dynamics of Transparent Exopolymer Particles in Marine Ecosystems

Transparent exopolymer particles (TEP) are gel-like assemblies of acidic polysaccharides produced by phytoplankton and bacteria. These particles form via abiotic coagulation of dissolved polymeric precursors or by direct cellular excretion during bloom events, creating a sticky matrix that binds organic debris, cells and mineral grains. By promoting aggregation, TEP accelerate the sinking of particulate organic matter and underpin the efficiency of the biological carbon pump. Microbial interactions—including colonisation by heterotrophic bacteria and infection by viruses or fungal parasites—modulate TEP production, composition and degradation, thereby influencing carbon remineralisation and sedimentation rates. Abiotic drivers such as turbulence, temperature and ultraviolet radiation further regulate TEP assembly and turnover. Collectively, these processes determine the distribution, longevity and ecological impact of TEP across surface, mesopelagic and deep-sea environments, with significant implications for global carbon cycling and climate feedbacks.

Research from Nature Portfolio

Recent studies have shown that fungal parasitism on diatoms markedly alters the formation and bio-physical properties of sinking aggregates. Infection enhances bacterial colonisation of phytoplankton cells, resulting in smaller, more labile aggregates with elevated carbon respiration and reduced settling velocities. In another advance, a fucose-containing sulphated polysaccharide secreted by bloom-forming diatoms has been identified as highly resistant to enzymatic breakdown. This polymer accumulates during blooms, acts as an adhesive binder in aggregate formation and thereby enhances vertical carbon export. These findings elucidate how specific biopolymer structures and host–microbe interactions govern TEP-mediated sequestration processes.

Dynamics of Transparent Exopolymer Particles in Marine Ecosystems publication trend

The graph below shows the total number of articles in dynamics of transparent exopolymer particles in marine ecosystems across all publications each year (not limited to Nature Index journals).

Technical terms

Transparent Exopolymer Particles (TEP): Gel-like acidic polysaccharide networks exuded by microorganisms, crucial for particle aggregation.

Marine Gel Particles (MGPs): Amorphous hydrogel exudates from marine microbes, encompassing TEP and related gel fractions.

Coomassie Stainable Particles (CSP): Proteinaceous gel particles detectable with Coomassie Blue dye, often occurring alongside TEP.

Biological Carbon Pump: The process whereby sinking particulate organic matter transports carbon from surface waters to the deep ocean for long-term storage.

Extracellular Polymeric Substances (EPS): A complex matrix of polysaccharides, proteins and nucleic acids secreted by cells, forming the structural backbone of biofilms and gel particles.

References

1. Fungal parasitism on diatoms alters formation and bio–physical properties of sinking aggregates. Communications Biology (2023).
2. Diatom fucan polysaccharide precipitates carbon during algal blooms. Nature Communications (2021).
3. Marine bacteria Alteromonas spp. require UDP-glucose-4-epimerase for aggregation and production of sticky exopolymer. mBio (2024).
4. Isolation and Staining Reveal the Presence of Extracellular DNA in Marine Gel Particles. Gels (2023).
5. Main drivers of transparent exopolymer particle distribution across the surface Atlantic Ocean. Biogeosciences (2019).