Observing individual bacteria interacting with the physical structure of mucus had never been possible, according to Bryce Inman, a postdoctoral researcher at UC San Diego’s Scripps Institution of Oceanography during the project.
Science Daily reported on October 8, 2026, that the sticky consistency of marine snow determines how much carbon reaches the deep ocean.
Marine snow consists of sinking clumps of waste, dead organisms, mucus, silt, and phytoplankton. These particles remove more than 10 gigatons of carbon from surface waters each year. Only about two gigatons reach depths sufficient for long-term storage lasting centuries or millennia, while bacteria consume the rest.
The four-year research effort began in 2021 when Inman set out to explore the internal structure of biological mucus, a domain he terms the mucoscape. Multiple early attempts failed before the team developed a working technique in 2025 combining 3D confocal microscopy and fluorescent molecules known as molecular rotors for viscosity mapping, Tech Times reported.
This technical combination let researchers observe the physical terrain of individual particles. Bacteria preferentially colonize less viscous areas near the particle surface. The denser, stickier regions deeper inside resist bacterial penetration, acting like a worm in an apple where the core is tough to chew through.
Laboratory experiments showed that particles with greater viscosity resisted bacterial degradation and fragmentation for extended periods. Computer simulations indicated these sticky particles descend to greater depths before breaking apart. Thick, gelatinous marine snow is capable of transporting upward of six times the carbon downward to the deep ocean compared to less dense aggregates.
The findings help explain why some sinking material transports carbon much farther down than other particles originating near the surface. Climate models estimating ocean carbon uptake have previously omitted particle viscosity as a variable. This oversight means current projections of how much carbon the ocean absorbs as the climate warms rest on an incomplete accounting.
The interactions between bacteria and mucus observed in marine snow extend to coral reefs, kelp forests, plant root systems, and human digestive tracts. Mucus possesses a complex internal structure with bulges and crevasses that influence bacterial behavior at scales smaller than individual microbes.
Financial support for the project was additionally supplied by the Simons Foundation alongside the Engineering and Physical Sciences Research Council. The study’s detailed physical measurements are documented in Science, with companion findings published in Nature Communications.
