Meadow Soil samples from Angelo, CA Genome sequencing and assembly

Methylotrophy and archaeal heterotrophy dominate carbon turnover below the grass root zoneAnnually, half of all plant-derived carbon is added to soil; most is rapidly respired to CO2 but some is exported to sustain life in lower horizons and the deeper biosphere. Little is known about the microbial communities that respond to these carbon pulses and the biochemical pathways involved. We found that bacterial degradation of methyl compounds was pronounced below the grass root zone in the Fall rainy season. This process limits supply of methyl compounds for methanogenesis in the deeper subsurface. Archaea, which comprised ~20% of microbial communities in deeper soil, degrade organic carbon, including aromatic compounds. Populations display dandelion-like patterns of diversity, and many affiliate with largely unknown bacterial and archaeal phyla, underlining the roles of novel organisms in soil carbon cycling.