Rhizosphere Underground: Unraveling the Role of Microbes in Stabilizing Carbon Pools in Soils
EMSL Project ID
48504
Abstract
Microorganisms are fundamental to biogeochemical processes, as microbial metabolism significantly contributes to the regulation of terrestrial carbon and nitrogen cycling. However, the impact of the community of soil microbes within the mycorrhizosphere has not been examined in detail due to the difficulty of tracking micro-scale processes in natural microbial communities in complex soil habitats. In 2010, a groundbreaking conceptual framework for a microbial carbon pump was proposed for microbial production of recalcitrant carbon and its storage in oceans. Successive idea of carbon pump that operates in terrestrial systems was proposed in 2011. We recognize this area of the microbial carbon pump in soils as a newly identified knowledge gap and a landmark field for emergent research, where EMSL’s unique capabilities and expertise can certainly have a strong impact on the research programmatic priorities of the Office of Biological and Environmental Research (BER).A team of researchers representing insightful expertise in environmental microbiology, biogeochemistry, molecular biology, soil dynamics and hydrology will develop an approach using a combination of multi-scale imaging and analytical tools for the correlated imaging, analytical and computational methods to investigate living and non-living rhizosphere components at scales relevant to micro-habitats. This platform will be used on a Pinus resinosa representative ecosystem to identify and to model interactions of individual microcosm components: roots, fungi, microbial communities and soil minerals. Special emphasis will be given to microbial extracellular polymeric substances (EPS), as well as microbial biofilms components that contribute to the formation of pools of biogenic products associated with mineral surfaces, such as soil organic matter (SOM). In particular, we will examine the current hypothesis that preferential association with mineral surfaces and soil pores is an important mechanism of carbon sequestration. Our imaging approach will provide fundamental highresolution 3d spatially resolved information that will contribute to the better understanding of the factors influencing carbon flux and C sequestration, and toward the scheme of the microbial carbon pump in soils. We hypothesize the mycorrhizal associations and bacterial biofilms will significantly alter mineral surfaces through sorption of microbial and plant debris and mineral weathering (dissolution/precipitation reactions). We anticipate that during this process, soil microbes and their EPS will play a critical role in inducing the release of sustenance cations from the minerals; these nutrients will be further transported via advection and diffusion upstream to the plant rhizomes. Meanwhile, the portion of the plant cell detritus and the senesced microbial biomass will be decomposed, transformed, stabilized and incorporated into the form of the carbon pools in soil. Depending on their chemical composition and spatial accessibility, they will become either short-turnover-time, labile moieties that can serve as an important source of energy for heterotrophic organisms in the below ground portion of ecosystem, or the non-labile, resilient, recalcitrant C source with long-term residence time. We will build upon our expertise in visualization bacterial extracellular polymeric substances by electron microcopy [8], and in-depth analyses of microbial polymers by GC/MS and FTICR to capture this dynamic process of accumulation and differentiation microbially-derived C in soils.
The goal of this proposed research is to create a pathway for correlated multidisciplinary investigation of this process at several levels of spatial and temporal resolution. This multifaceted team approach will establish a standard scheme for a wide variety of follow-up research projects, based on changing the reaction conditions, e.g. temperature increase, studying the drying and rewetting cycles and drought response as a model for climate change, as well as for future application to other environmentally–important plant genera, such as a BER biofuel program relevant Setaria sp., bioenergy feed stock switchgrasses, and other systems.
Project Details
Start Date
2014-04-24
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator