Title: Taxon-specific microbial growth and mortality patterns reveal distinct temporal population responses to rewetting in a California grassland soil

Abstract

Microbial activity increases after rewetting dry soil, resulting in a pulse of carbon mineralization and nutrient availability. The biogeochemical responses to wet-up are reasonably well understood and known to be microbially mediated. Yet, the population level dynamics, and the resulting changes in microbial community patterns, are not well understood as ecological phenomena. In this work, we used sequencing of 16S rRNA genes coupled with heavy water (H₂¹⁸O) DNA quantitative stable isotope probing to estimate population-specific rates of growth and mortality in response to a simulated wet-up event in a California annual grassland soil. Bacterial growth and mortality responded rapidly to wet-up, within 3 h, and continued throughout the 168 h incubation, with patterns of sequential growth observed at the phylum level. Of the 37 phyla detected in the prewet community, growth was found in 18 phyla while mortality was measured in 26 phyla. Rapid growth and mortality rates were measurable within 3 h of wet-up but had contrasting characteristics; growth at 3 h was dominated by select taxa within the Proteobacteria and Firmicutes, whereas mortality was taxonomically widespread. Furthermore, across the community, mortality exhibited density-independence, consistent with the indiscriminate shock resulting from dry-down and wet-up, whereas growth was density-dependent, consistentmore » with control by competition or predation. Total aggregated growth across the community was highly correlated with total soil CO₂ production. Together, these results illustrate how previously “invisible” population responses can translate quantitatively to emergent observations of ecosystem-scale biogeochemistry.« less

Authors:

Blazewicz, Steven J. ^[1]; Hungate, Bruce A.  ^[2];

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Koch, Benjamin J. ^[2]; Nuccio, Erin E.  ^[3];

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Morrissey, Ember  ^[4];

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Brodie, Eoin L.  ^[5];

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Schwartz, Egbert ^[2]; Pett-Ridge, Jennifer  ^[3];

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• Search DOE PAGES for ORCID "0000-0002-4439-2398"
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Firestone, Mary K. ^[5]

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+ Show Author Affiliations

1. Univ. of California, Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2. Northern Arizona Univ., Flagstaff, AZ (United States)
3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
4. West Virginia Univ., Morgantown, WV (United States)
5. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Publication Date:

2020-03-12

Research Org.:

Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Northern Arizona Univ., Flagstaff, AZ (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1661052

Report Number(s):

LLNL-JRNL-769859
Journal ID: ISSN 1751-7362; 960485

Grant/Contract Number:  

AC52-07NA27344; DEB-1011093; SCW1632; SC0016207; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

The ISME Journal

Additional Journal Information:

Journal Volume: 14; Journal Issue: 6; Journal ID: ISSN 1751-7362

Publisher:

Nature Publishing Group

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; 59 BASIC BIOLOGICAL SCIENCES