Bathyarchaeia, The Deep Sea Microbes with a Hunger for Carbon

By: Viviana Valeria Rodriguez

The figure above is from the summarized article below. 
a) Here is a depiction of the BDGT-0 chemical structure. b) The LC-MS data showing peaks that confirm Bathyarchaeia producing unique BDGT lipids, with the placement of each peak identifying the lipid and height indicating its abundance.  (Dong et al., 2025) 

    When we think about ocean life, fish and coral reefs usually come to mind, but some of the most influential organisms cannot be seen with the human eye. Bathyarchaeia, a group of microbes deep in seafloor sediments, are among the most abundant archaea on Earth. Just recently, their role and importance in the carbon cycle have been properly understood. This study demonstrates that Bathyarchaeia can absorb carbon from both dissolved inorganic carbon (CO2) and organic matter from plants like lignin. They then can convert these carbons into a unique membrane lipid called butanetriol dialkyl glycerol tetraethers (BDGTs), which are structurally different from the more common lipids made by most other organisms known as glycerol. This dual strategy of two different resources allows them to be highly adaptable in nutrient limited environments. The importance of this discovery lies in how it reshapes our understanding of the carbon cycle. By recycling both "fresh" and "old" carbon into their cell structures, Bathyarchaeia play a crucial role in long term carbon storage in marine sediments. The distinctive lipids that they possess may also serve as a biomarker. Biomarkers help scientists track microbial activity in oceans and readjust carbon cycling in old environments. In short, these hidden microbes serve as powerful recyclers that silently impact Earth's climate system, reminding us that big change can come from the smallest things. 

Original article:

Dong, L., Jing, Y., Hou, J., Zhou, J., Yu, T., Chen, S., Liang, L., Zhu, P., Zhu, P., Zhao, X., Hinrichs, K.-U., & Wang, F. (2025). A dominant subgroup of marine Bathyarchaeia assimilates organic and inorganic carbon into unconventional membrane lipids. Nature Microbiology.
https://doi.org/10.1038/s41564-025-02121-5