Quantitative Stable-Isotope Probing (qSIP) with Metagenomics Links Microbial Physiology and Activity to Soil Moisture in Mediterranean-Climate Grassland Ecosystems

Alex Greenlon, Ella Sieradzki, Olivier Zablocki, Benjamin J. Koch, Megan M. Foley, Jeffrey A. Kimbrel, Bruce A. Hungate, Steven J. Blazewicz, Erin E. Nuccio, Christine L. Sun, Aaron Chew, Cynthia Jeanette Mancilla, Matthew B. Sullivan, Mary Firestone, Jennifer Pett-Ridge, Jillian F. Banfield

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The growth and physiology of soil microorganisms, which play vital roles in biogeochemical cycling, are shaped by both current and historical soil environmental conditions. Here, we developed and applied a genome-resolved metagenomic implementation of quantitative stable isotope probing (qSIP) with an H218O labeling experiment to identify actively growing soil microorganisms and their genomic capacities. qSIP enabled measurement of taxon-specific growth because isotopic incorporation into microbial DNA requires production of new genome copies. We studied three Mediterranean grassland soils across a rainfall gradient to evaluate the hypothesis that historic precipitation levels are an important factor controlling trait selection. We used qSIP-informed genome-resolved metagenomics to resolve the active subset of soil community members and identify their characteristic ecophysiological traits. Higher year-round precipitation levels correlated with higher activity and growth rates of flagellar motile microorganisms. In addition to heavily isotopically labeled bacteria, we identified abundant isotope-labeled phages, suggesting phage-induced cell lysis likely contributed to necromass production at all three sites. Further, there was a positive correlation between phage activity and the activity of putative phage hosts. Contrary to our expectations, the capacity to decompose the diverse complex carbohydrates common in soil organic matter or oxidize methanol and carbon monoxide were broadly distributed across active and inactive bacteria in all three soils, implying that these traits are not highly selected for by historical precipitation.

Original languageEnglish (US)
Article numbere00417-22
JournalmSystems
Volume7
Issue number6
DOIs
StatePublished - Dec 2022

Keywords

  • metagenome-assembled genomes
  • metagenomics
  • soil microbiome
  • soil moisture
  • stable isotope probing

ASJC Scopus subject areas

  • Microbiology
  • Physiology
  • Biochemistry
  • Ecology, Evolution, Behavior and Systematics
  • Modeling and Simulation
  • Molecular Biology
  • Genetics
  • Computer Science Applications

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