Scientists recovered intensely blue serpentinite mud from mud volcanoes near the Mariana Trench at about 3,000 m depth and found intact lipids from bacterial and archaeal membranes, indicating living extremophile communities. The sediment is highly alkaline (pH ~12) and nutrient-poor, yet supports chemosynthetic microbes that metabolize methane and reduce sulfate, producing hydrogen sulfide. These findings confirm active subsurface life in dense serpentinite mud and may offer insights into how life could have originated on early Earth.
Striking Blue Volcanic Mud at 3,000 m Harbors Living Microbes — Clues to Early Life
Scientists recovered intensely blue serpentinite mud from mud volcanoes near the Mariana Trench at about 3,000 m depth and found intact lipids from bacterial and archaeal membranes, indicating living extremophile communities. The sediment is highly alkaline (pH ~12) and nutrient-poor, yet supports chemosynthetic microbes that metabolize methane and reduce sulfate, producing hydrogen sulfide. These findings confirm active subsurface life in dense serpentinite mud and may offer insights into how life could have originated on early Earth.
04:10 PM, 11/10/2025Science
Blue serpentinite mud from near the Mariana Trench hosts active extremophiles
Researchers have recovered vividly blue volcanic mud from mud volcanoes near the Mariana Trench at nearly 3,000 meters (9,833 feet) depth and found molecular evidence that living microbes persist in this extreme environment.
The samples, collected during the 2022 R/V Sonne expedition SO292/2, include cores from the Pacman mud volcano. The lower sections of one core are composed largely of serpentinite with fragments of brucite, and have remained isolated from overlying seawater — preserving an intense blue color. Closer to the seafloor the sediment fades to a paler blue-green where brucite has dissolved after exposure to salt water.
Despite being nutrient-poor and extremely alkaline (pH ~12), the serpentinite layers contain intact lipids characteristic of bacterial and archaeal cell membranes. Those membrane fats act as microbes' first line of defense in hostile, high-pH conditions, and their mostly intact state indicates living, metabolically active microbial communities rather than only ancient remnants.
"It is simply exciting to obtain insights into such a microbial habitat because we suspect that primordial life could have originated at precisely such sites," says Florence Schubotz, an organic geochemist at the University of Bremen. She adds that finding life under very high pH and low organic-carbon conditions is particularly remarkable.
Palash Kumawat and colleagues (University of Bremen) report that the molecular signatures reveal a sharp shift in organism types between pelagic ocean-floor sediment and the serpentinite mud. The team found evidence for chemosynthetic metabolisms: microbes that harvest energy from methane while reducing sulfate, a process that generates corrosive hydrogen sulfide. Until now, the presence of methane-producing microorganisms in these serpentinite mud systems had been presumed but not directly confirmed.
Serpentinites are known to support chemosynthetic life elsewhere on the seafloor; this study shows similar communities can thrive deeper in dense serpentinite mud. Life beneath the seafloor is estimated to constitute roughly 15% of Earth’s biomass and plays an important role in global nutrient cycles, yet much about it remains unknown.
Kumawat and collaborators plan further study of these extremophiles to learn what they might reveal about the origins of life on an early Earth that was far less hospitable than today. The research is published in Communications Earth & Environment.