Nonliving respiration: Another breath in the soil?

The present study challenges the traditional view that the respiration of organic carbon to CO 2 is an exclusively intracellular process, revealing that organic compound respiration can occur spontaneously in an extracellular context in soils. Using 1 H nuclear magnetic resonance spectroscopy to analyze the dynamics of the sterile soil exometabolomes alongside C-CO 2 flux analyses and sterile soil fuel cells, we show that soil catalysts facilitate a diverse array of substrate-driven reactions, leading to the complete oxidation of organic compounds to CO 2 with O 2 consumption. Our results indicate that soil particles are capable of transferring electrons from substrates to the final acceptor, thereby sustaining metabolism-like processes independently of living cells. Notably, some soil catalysts and induced respiration remain stable for more than 6 years. These findings support the coexistence of cellular and noncellular metabolic pathways in soil respiration.