Parched: quantifying microbial ecophysiology and the fate of plant carbon during soil dry down
EMSL Project ID
60447
Abstract
In seasonally dry grasslands, soil microbes bloom during the plant growing season, survive extreme desiccation (water potential < -35 MPa) during long dry periods, and then rapidly mineralize soil carbon (C) minutes after the first rain of the wet season. The characteristics that allow these microbes to survive under extremely dry conditions and persist through rapid changes in resource availability and water potential are likely important traits for soil C dynamics. We hypothesize that soil water dynamics regulate microbiome metabolic state (growing, dying, dormant) and microbial residue production, controlling the quantity and molecular composition of soil C. To determine how soil moisture shapes microbiome interactions, ecophysiological traits, and trait expression that affects the fate of cellular C, we are studying the 'Dry-Down' transition between the wet spring growing season and the hot dry summer that are characteristic of Mediterranean grasslands. A key feature of this study is our focus on in situ analysis: paired gene expression and quantitative stable isotope probing (qSIP) measurements of activity and ecophysiological traits in metagenomes and viromes in intact soil systems sampled with high temporal resolution. With a suite of high molecular resolution soil C measurements, we will track the transformations of soil organic matter (SOM) and microbial exometabolites over time to understand changes in the C chemistry of the labile and dissolved pool during soil drying.
Our specific objectives and associated JGI/EMSL resource requests are: 1) Develop a highly resolved understanding of the traits - and expression of traits - that predict mineral-associated C, and the associated microbial and viral taxa: (JGI: 1Tb of virome, metagenome (SIP metagenome fractions processed by LLNL) and metatranscriptome sequencing; EMSL: 48 metaproteomes), 2) Measure dynamics of SOM and soil metabolites: (EMSL: 96 FTICR, 48 lipidomes, 48 LC-MS metabolomes and 48 liquid-state NMR metabolomes), 3) Assess how dry-down affects the microscale structure of SOM-mineral associations: (EMSL: 24 He ion and TEM imaging, solid-state 13C NMR).
Project Details
Project type
FICUS Research
Start Date
2022-10-01
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members