MICROBES PERSIST: SYSTEMS BIOLOGY OF THE SOIL MICROBIOME
EMSL Project ID
51022
Abstract
Soils store more carbon than the atmosphere and biosphere combined, yet the mechanisms that regulate soil C remain elusive. While plant roots are the initial source of carbon (C) that enters belowground food webs, it is the microbial transformation of this C that determines whether it is retained as soil organic matter (SOM) or returned back to the atmosphere (CO2, CH4). Since soil C and associated organic molecules are so critical to soil fertility, water holding capacity, and the C balance of our planet, a predictive understanding of soil C residence time and turnover (i.e. ‘persistence’) is essential. It has recently become clear that microbial cell materials (‘necromass’) play a critical role in the persistence of SOM. However, current soil C models continue to emphasize stabilization by abiotic mechanisms (sorption, occlusion, and recalcitrance), largely ignoring the impacts of microbial ecophysiology. Our SFA team hypothesizes that microbial biochemistry, functional potential and physiology may be of comparable, or greater importance relative to abiotic (e.g. mineralogy) stabilizing effects. We further suggest that the basis of microbial impacts results from their specific ecophysiological ‘traits’ (e.g. cell wall composition, hyphal growth, EPS production, spore formation, carbon use efficiency, extracellular enzymes, adhesion genes, and specific growth rate) that can be genomically resolved through soil metagenomics and quantified via isotope tracing. Testing this expectation is one of the key goals for our SFA program.
In our SFA research, we have chosen to focus on rainfall and soil water content --since these are master controllers of microbial growth and death and SOM stabilization processes in soil. In addition, Earth system models project major changes in precipitation in temperate regions. However, we currently do not have a mechanistic or predictive understanding of how altered soil moisture regimes will affect soil C persistence and microbial populations dynamics. Previous work suggests microbial ecophysiology may be a key factor controlling soil C dynamics as water availability changes. We posit that interactions between the soil water cycle and phage-host dynamics may also control a significant proportion of soil C flux, but this nascent research area is a major knowledge gap. The intensity and timing of precipitation not only affects soil microbial community composition and microbial ecological strategies, but also microbial-controlled decomposition, carbon use efficiency, and soil CO2 efflux—setting the stage for the work proposed here. The ultimate goal of our Soil Microbiome Scientific Focus Area (SFA) is to determine how microbial ecophysiology, population dynamics, and microbe-mineral interactions regulate cellular-C persistence under changing moisture regimes.
Project Details
Start Date
2019-08-22
End Date
2021-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Team Members