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Microbial control of mineral-bound carbon


EMSL Project ID
60189

Abstract

The formation of organo-mineral complexes, particularly in the deep soil horizons is a key process in the long-term stabilization and therefore persistence of carbon in soils. However, there is a knowledge gap in carbon cycling research regarding the fundamental understanding of the controls on the accumulation of soil carbon and how it’s influenced by the soil microbial community. The work proposed here builds upon a strong foundation of research conducted by the DOE BER- Science Focus Area (SFA) at LANL, which aims to expand upon carbon management strategies and to help address this gap in knowledge. To understand key mechanisms that underlie the microbial control on the persistence of carbon in soils, we employed a well-established common garden approach1, 2, using microcosms (n > 200) to examine the carbon flow (CO2) of > 100 distinctive subsurface microbial communities desorbing, decomposing, and respiring carbon bound to kaolinite, a common soil mineral over a 105-day incubation. We 1) assessed the magnitude of microbial-driven variation in mineral associated organic matter (MAOM) subsurface decomposition and; 2) examined microbial features (16S & fungi) associated with divergent patterns of carbon flow. To identify specific community features (traits at the community, organism, and molecular levels) linked to the variation in MAOM decomposition, the microbial communities representing the highest and lowest (‘high’ and ‘low’) respiration (CO2) profiles were down-selected for community profiling.
In a partnership with EMSL, we propose to expand the depth of the current study and specifically aim to delineate which elemental compositions (i.e., C-C, O-C=O) and compound classes (i.e., proteins, lipids) remain bound to kaolinite after microbial processing and compare this to the original carbon composition of the control samples (OM bound to kaolinite). We propose to use X-ray Photoelectron Spectroscopy (XPS) and FT-ICR to characterize the remaining carbon profiles. We will integrate this data with bacterial (16S rRNA) and fungal (ITS) compositional data to gain insight into microbial controls of MAOM abundance and diversity, thus expanding our current knowledge on the persistence of SOC.

Project Details

Project type
Exploratory Research
Start Date
2021-12-01
End Date
2022-09-30
Status
Closed

Team

Principal Investigator

Marie Kroeger
Institution
Los Alamos National Laboratory

Co-Investigator(s)

Joany Babilonia
Institution
Los Alamos National Laboratory

Sanna Sevanto
Institution
Los Alamos National Laboratory

John Dunbar
Institution
Los Alamos National Laboratory