Microbes deep beneath seafloor survive on byproducts of radioactive process

Mar 2, 2021

Researchers look at the contribution of water radiolysis to life in the deep biosphere. Results now published in the journal Nature Communications.

The sample material from the deep biosphere that was analyzed for the study came, among others, from the IODP Expedition 329 with the research drilling ship JOIDES RESOLUTION. Here, the ship is moored in the harbor of Papeete, Tahiti, before the start of the expedition. Copyright: John Beck, Integrated Ocean Drilling Program, U.S. Implementing Organization (IODP USIO).

In a process called radiolysis, water is broken down into its component parts by ionizing radiation. In wet sediment and rock, this natural process continuously produces hydrogen as well as other oxidized chemical substances. As the primary electron donor, this radiolytic hydrogen is the food source for microorganisms in continental aquifers living several kilometers below the Earth's surface and is thus of great importance. However, the extent to which most submarine ecosystems rely on radiolytic products has been poorly constrained.

With new analyses, a team of scientists led by the University of Rhode Island, Graduate School of Oceanography, has succeeded in quantifying radiolytic hydrogen production in marine sediments. The research shows that in the deep biosphere ancient microbes derive their energy from hydrogen and oxidants originating from radiolytic production and thus survive. In some cases, the hydrogen yield from radiolysis was twenty-seven times higher than in pure water. The results indicate that certain minerals in the marine sediment lead to this significant increase.

Dr. Chloe Anderson, a scientist from MARUM – Center for Marine Environmental Sciences at the University of Bremen is also involved in the study, which has now been published in the journal Nature Communications.

Original publication: Sauvage, J.F., Flinders, A., Spivack, A.J. et al. The contribution of water radiolysis to marine sedimentary life. Nat Commun 12, 1297 (2021). https://doi.org/10.1038/s41467-021-21218-z