How Sequential Expression Mediates Soil Carbon Stabilization and Turnover
Two-thirds of the carbon (C) in the terrestrial biosphere is stored as soil organic C and plant roots are the primary source of C that becomes stabilized in soil. Over time, living roots become root debris and undergo decomposition by soil microbes. It is now understood that most plant C is utilized or transformed by soil microorganisms en route to stabilization. Therefore, the composition and metabolic activities of soil microbial communities are critical to understanding soil carbon stabilization. The change in composition and function of the C-transforming microbial communities over time defines the biological component of soil C stabilization.
We are determining the successional patterns, in particular metabolic capabilities and identities of root-C utilizing microbial communities from active root exudation to stabilization as mineral-associated soil C. We also investigate the influence of elevated CO2 on functional gene expression associated with C movement into stabilized soil pools, and are identifying gene expression networks in order to model the microbial community cascades which mediate C stabilization and turnover. Our group is poised to make two significant contributions to the scientific community by 1) isolating and sequencing functional transcriptomes targeted through stable isotope probing (SIP), and 2) mapping in-situ C utilization and microbial identity in soil with nanometer resolution (NanoSIMS). This study will forge a critical temporal and spatial link between the fate of root-derived C and the creation of stabilized soil organic C.
This project is funded by the Department of Energy, Biological and Environmental Research, Genomic Science program.