On Nov. 9, 2025, scientists from the Center for Marine Environmental Sciences, University of Bremen reported they had uncovered thriving microbial life in one of Earth’s harshest environments—an area with a pH of 12, where survival seems nearly impossible.

Using lipid biomarkers instead of DNA, researchers revealed how these microbes persist by metabolizing methane and sulfate. The discovery not only sheds light on deep-sea carbon cycling but also suggests that life may have originated in similar extreme conditions, offering a glimpse into both Earth’s past and the limits of life itself.

In a new study, first author Palash Kumawat from the University of Bremen’s Geosciences Department and his team investigated how microbes manage to survive in one of the planet’s harshest underwater environments. They analyzed lipid biomarkers, specialized fat molecules that reveal biological activity, to uncover the organisms’ survival strategies. The site’s pH of 12 makes it one of the most alkaline environments ever documented, creating conditions that are exceptionally difficult for life to endure.

Microbial life in the deep ocean plays an important role in the global carbon cycle, processing carbon and other elements far below the surface. The communities identified by Kumawat’s team draw their energy not from sunlight but from minerals in rocks and gases like carbon dioxide and hydrogen, producing methane in the process — an important greenhouse gas. These biochemical reactions occur independently of the ocean above, showing that these microbes operate in a self-contained ecosystem.

The lipid molecules also help determine whether the microbes are alive or remnants from ancient communities. Intact biomolecules suggest active or recently living cells, while degraded ones indicate fossilized “geomolecules” from long ago. Kumawat explains that combining isotope data with lipid biomarkers shows evidence of both modern and ancient microbial populations inhabiting this hostile environment. “This distinction helps us when working in areas with extremely low biomass and nutrient deficiency,” he notes.

The team’s samples came from sediment cores collected in 2022 during Expedition SO 292/2 aboard the Research Vessel Sonne. During this mission, scientists discovered previously unknown mud volcanoes in the Mariana forearc region and were able to collect samples directly from them.

The work forms part of the Cluster of Excellence “The Ocean Floor — Earth’s Uncharted Interface.” Building on their findings, Kumawat and his colleagues now plan to cultivate these microorganisms in controlled incubators to learn more about how they obtain nutrients and persist in such inhospitable environments.