Title: Simple Plant and Microbial Exudates Destabilize Mineral-Associated Organic Matter via Multiple Pathways

Abstract

Most mineral-associated organic matter (MAOM) is protected against microbial attack, thereby contributing to longterm carbon storage in soils. However, the extent to which reactive compounds released by plants and microbes may destabilize MAOM and so enhance microbial access, as well as the underlying mechanisms, remain unclear. Here, we tested the ability of functionally distinct model exudates (ligands, reductants, and simple sugars) to promote microbial utilization of monomeric MAOM, bound via outer-sphere complexes to common iron and aluminum (hydr)oxide minerals. The strong ligand oxalic acid induced rapid MAOM mineralization, coinciding with greater sorption to and dissolution of minerals, suggestive of direct MAOM mobilization mechanisms. In contrast, the simple sugar glucose caused slower MAOM mineralization, but stimulated microbial activity and metabolite production, indicating an indirect microbially-mediated mechanism. Catechol, acting as reductant, promoted both mechanisms. While MAOM on ferrihydrite showed the greatest vulnerability to both direct and indirect mechanisms, MAOM on other (hydr)oxides was more susceptible to direct mechanisms. These findings suggest that MAOM persistence, and thus longterm carbon storage within a given soil, is not just a function of mineral reactivity but also depends on the capacity of plant roots and associated microbes to produce reactive compounds capable of triggering specific destabilizationmore » mechanisms.« less

Authors:

Li, Hui ^[1]; Bölscher, Tobias ^[2]; Winnick, Matthew ^[3]; Tfaily, Malak M.  ^[4];

• Search DOE PAGES for author "Tfaily, Malak M."
• Search DOE PAGES for ORCID "0000-0002-3036-2833"

Cardon, Zoe G. ^[5]; Keiluweit, Marco  ^[1]

• Search DOE PAGES for author "Keiluweit, Marco"
• Search DOE PAGES for ORCID "0000-0002-7061-8346"

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+ Show Author Affiliations

1. Stockbridge School of Agriculture and School of Earth & Sustainability, University of Massachusetts, Amherst, Massachusetts 01003, United States
2. Stockbridge School of Agriculture and School of Earth & Sustainability, University of Massachusetts, Amherst, Massachusetts 01003, United States, Department of Biology, Lund University, 223 62 Lund, Sweden
3. Department of Geosciences, University of Massachusetts, Amherst, Massachusetts 01003, United States
4. Department of Environmental Science, University of Arizona, Tucson, Arizona 85719, United States
5. The Ecosystems Center, Marine Biological Laboratory, Woods Hole, Massachusetts 02543, United States

Publication Date:

Mon Feb 15 00:00:00 EST 2021

Research Org.:

Marine Biological Laboratory, Woods Hole, MA (United States); Univ. of Massachusetts, Amherst, MA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Biological and Environmental Research (BER)

OSTI Identifier:

1777582

Alternate Identifier(s):

OSTI ID: 1774962

Grant/Contract Number:  

SC0019142; SC0019477

Resource Type:

Published Article

Journal Name:

Environmental Science and Technology

Additional Journal Information:

Journal Name: Environmental Science and Technology Journal Volume: 55 Journal Issue: 5; Journal ID: ISSN 0013-936X

Publisher:

American Chemical Society

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; Mineral-associated organic matter; root exudates; soil carbon; iron minerals; aluminum minerals; ligands; microbial mineralization; carbohydrates; mineralization; dissolution; aromatic compounds; minerals