An unknown oxidative metabolism substantially contributes to soil CO₂ emissions

• Main Authors: T. Shahzad, V. Perrier, A.-C. Lehours, M. Joly, E. Dubreucq, R. Despinasse, A. Comby, J. Colombet, G. Alvarez, V. Maire, S. Fontaine
• Format: Article
• Language: English
• Published: Copernicus Publications 2013-02-01
• Series: Biogeosciences
• Online Access: http://www.biogeosciences.net/10/1155/2013/bg-10-1155-2013.pdf

The respiratory release of CO₂ from soils is a major determinant of the global carbon cycle. It is traditionally considered that this respiration is an intracellular metabolism consisting of complex biochemical reactions carried out by numerous enzymes and co-factors. Here we show that the endoenzymes released from dead organisms are stabilised in soils and have access to suitable substrates and co-factors to permit function. These enzymes reconstitute an extracellular oxidative metabolism (EXOMET) that may substantially contribute to soil respiration (16 to 48% of CO₂ released from soils in the present study). EXOMET and respiration from living organisms should be considered separately when studying effects of environmental factors on the C cycle because EXOMET shows specific properties such as resistance to high temperature and toxic compounds.