Feedbacks between microbial community dynamics and the persistence of soil organic carbon
EMSL Project ID
51095
Abstract
Soil organic matter (SOM) is the largest active carbon reservoir in the terrestrial environment and significantly influences soil fertility, water quality, global C cycling and associated feedbacks to Earth's climate system. It is increasingly being recognized that the products of microbial metabolism as well microbial residues constitute a large fraction of (SOM) and represent a historically overlooked nutrient pool. Despite the importance of microbial contributions to SOM, we lack empirical evidence of the chemical constituents of microbial necromass and how different groups of microorganisms contribute to its production and persistence. In the proposed work, we aim to fill this gap by generating the much-needed molecular information to validate or refute existing conceptual models. We seek to understand the microbial metabolic and physiological traits that contribute to SOM dynamics, which are fundamental to C, N, and P cycles and, in turn, soil, water, and nutrient status. We propose to characterize the composition of microbially produced organic matter with an emphasis on compound classes that persist in soils over time. We will achieve this by conducting a long-term 13C tracer incubation experiment to track the incorporation, turnover, persistence, and composition of microbial necromass in soil. Incubations will be conducted on soils collected from corn and switchgrass plots at the DOE Great Lakes Bioenergy Research Center fields sites in Wisconsin and Michigan. We propose to combine stable isotope probing with multi-omics to track the production, recycling, persistence, and molecular composition of microbial residues. Specifically, we will extract proteins, lipids and polar metabolites from three timepoints and quantify the amount of labeled carbon in each fraction to identify the dynamics of microbial derived organic over time. Our approach of connecting -omics information (metabolomic, lipidomic) to carbon and nutrient cycling will enable us to not only identify the chemical composition of microbially derived SOM, but also gain insights to which microbial groups and metabolic pathways are involved in generating persistent microbial residues. In addition, we propose to conduct a small ssNMR analysis on the microbial necromass remaining in the soil after our targeted extraction to characterize the most persistent microbially derived molecules. Through this exploratory proposal, we aim to develop a molecular understanding of the fundamental ecological, biogeochemical and microbial processes regulating the accumulation and persistence of microbial residues in soil. Focusing on two soils and two biofuel cropping systems will enable us to analyze our results in a broader context in a way that supports the mission of the DOE. By collaborating with EMSL and user staff, we will link microbial populations and traits to the molecular biochemistry that is regulating C and nutrient cycling in soil, which is central to the BER mission.
Project Details
Project type
Exploratory Research
Start Date
2019-11-26
End Date
2021-03-31
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members