In Situ Stable Isotope Probing of Methanogenic Archaea in the Rice Rhizosphere

Microorganisms living in anoxic rice soils contribute 10 to 25% of global methane emissions. The most important carbon source for CH 4 production is plant-derived carbon that enters soil as root exudates and debris. Pulse labeling of rice plants with 13 CO 2 resulted in incorporation of 13 C into the ribosomal RNA of Rice Cluster I Archaea in the soil, indicating that this archaeal group plays a key role in CH 4 production from plant-derived carbon. This group of microorganisms has not yet been isolated but appears to be of global environmental importance.