在一个长达15年的研究计划中，Sébastien Fontaine和他的团队调查了无菌土壤中的碳释放。在使用伽马辐射消灭土壤微生物后，他们观察到二氧化碳排放量有所下降，但稳定维持了100天以上。最终，这些灭菌的土壤样本持续消耗氧气并释放二氧化碳达6年之久，且在第1,606天和第2,442天时仍验证了可测量的排放量。

为了探索潜在的机制，研究人员Clémentin Bouquet和Benoit Kéraval分析了添加葡萄糖的土壤，这些土壤表现出更高的排放率。透过电子显微镜，他们证实细胞已经死亡，且缺乏RNA或DNA。此外，利用装有近5年前被辐射照射之土壤的土壤燃料电池，他们检测到的电流显著高于盐水对照组，并在6个月大的无菌土壤样本中识别出8个克氏循环中间分子中的4个。

这些发现表明，代谢反应可以在没有活细胞的情况下发生。有机化学家Joseph Moran和生物化学家Markus Ralser提出，土壤中的金属催化剂（如铁氧化物和铝氧化物）可以驱动这些生命前的反应。尽管天体生物学家Sudha Rajamani认为持续存在的酶可能会催化这些反应，但Fontaine指出，酶活性呈指数级下降，且目前已知没有任何酶能存活6年，这使得纯酶学的解释极不可能。

During a 15-year research effort, Sébastien Fontaine and his team investigated carbon release from sterile soil. After using gamma radiation to eliminate soil microbes, they observed that carbon dioxide emissions declined but stabilized for over 100 days. Ultimately, the sterilized soil samples continued to consume oxygen and release carbon dioxide for 6 years, with measurable emissions verified at days 1,606 and 2,442.

To explore the underlying mechanisms, researchers Clémentin Bouquet and Benoit Kéraval analyzed glucose-augmented soils, which exhibited higher emission rates. Using electron microscopy, they verified that the cells were dead, lacking RNA or DNA. Furthermore, using a soil-based fuel cell with soil irradiated nearly 5 years prior, they detected an electrical current significantly higher than a saltwater control, and identified 4 out of 8 Krebs cycle intermediate molecules in 6-month-old sterile soil samples.

These findings suggest that metabolic reactions can occur without living cells. Organic chemist Joseph Moran and biochemist Markus Ralser propose that metal catalysts in soil, such as iron and aluminum oxides, could drive these pre-biotic reactions. Although astrobiologist Sudha Rajamani suggests persisting enzymes might catalyze these reactions, Fontaine notes that enzyme activity decreases exponentially and no known enzyme survives for 6 years, making a purely enzymatic explanation highly unlikely.