The role of microbial predation and cooperation on soil carbon pathways measured through multi-omics
EMSL Project ID
60861
Abstract
Soil microorganisms drive the decomposition of terrestrial carbon, releasing CO2 into the atmosphere and retaining additional pools belowground. Thus, a critical parameter in climate modeling efforts is the proportion of carbon (C) in the soil assimilated into microbial biomass vs. lost to respiration (carbon use efficiency or CUE). Initially CUE is governed by microbial metabolic pathways (i.e., biochemical efficiency) but over longer time intervals it is influenced by how quickly soil C is released, recycled, and re-assimilated throughout the microbial community (i.e., turnover). Predator-prey interactions are a high priority for research because they govern global carbon turnover and CUE in oceans and may play a similar role in soil. However, the effect of predation on soil C loss or accrual under changing environmental conditions is not well quantified, and cooperative interactions are similarly underdetermined. This proposal aims to determine how microbial interactions to control soil C balance in response to experimental drought.
The proposed research will conduct labeled isotope tracer incubations to follow the movement of plant and microbial C under different moisture and predator manipulations. Our specific hypotheses are that H1) Predation will have no effect on instantaneous biochemical efficiency but will reduce community-scale CUE by increasing energy flow through predator populations; H2) Water limitation will dampen energy flow through added predators and will broadly reduce transcription of genes associated with antagonistic interactions (including predation and predator defense); and H3) phagocytosis (“cell-eating”) by protists will promote C loss through respiration whereas cell lysis by predatory bacteria will promote C accrual and retention in soil. Soils (taken adjacent to a 23-year warming experiment in northern Arizona where parallel research is to be initiated) will be inoculated with either protists or predatory bacteria (Bdellovibrio spp.) and kept at 30% and 60% of their water holding capacity. Multiple sampling times will capture short and long-term dynamics: 15, 45, 90, and 360 days. This project will generate multiple data streams including metagenomics, metatranscriptomics, 13C and 18O quantitative stable isotope probing, metabolic flux analysis, 13C-CO2 respiration, microbial biomass and community-scale CUE, mineral-associated 13C composition (13C-ssNMR, LC-MS), dissolved organic matter and metabolomics composition (FTICR-MS). All treatments will be replicated in two-species pore-scale micromodel habitats where predator and prey population densities will be manipulated in addition to soil moisture.
Data from this experiment will be used to more rigorously combine soil C processing with organismal interactions by leveraging stable isotope tracing to quantify the movement of plant C into distinct microbial populations (bacteria, archaea, fungi, protists, and viruses) at a high resolution therein concretely identifying cross-species metabolic interactions. These data will thus address the critical knowledge gap of how and when microbial interactions accelerate soil C cycling.
Project Details
Project type
FICUS Research
Start Date
2023-10-01
End Date
N/A
Status
Active
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members