What appear to be biochemical processes may be a natural feature of geology
Sterilized soil continues releasing CO2 for years, suggesting biochemical reactions occur without living cells.
French biochemist Sébastien Fontaine's lab sterilized soil with gamma radiation to measure carbon release from nonliving dirt. Instead of stopping, the soil kept emitting CO2 for six years. The team added enzymes, which spiked emissions, suggesting metabolic processes like the Krebs cycle operate in soil without cells. They detected electron flow through sterile soil using a fuel cell and found four intermediates of the Krebs cycle in six-month-old samples. Researchers proposed that minerals and metals in soil can catalyze these reactions naturally. The findings suggest such chemistry may predate life on Earth and could be more common than assumed.
Some experts argue enzymes from dead cells likely explain the results, persisting and functioning even after fragmentation. Others note that no enzyme is known to remain active for six years. The discovery raises questions about distinguishing life from nonlife in soil and implications for detecting metabolism on Mars.
What HN community is saying
Most commenters accept the finding but emphasize that lingering enzymes from dead cells likely explain the observations, not spontaneous mineral-catalyzed reactions. One commenter notes enzyme fragments retain catalytic activity even after degradation. Mars implications noted: the research could cause false positives if searches detect only metabolic products. A tangential exchange references the Brookhaven Gamma Forest (1961-1978), where irradiated forest soil still shows limited recovery decades later. One commenter mentioned knowing someone at the research lab. Limited skepticism; thread leans toward technical discussion of mechanisms rather than debating the core claim.