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Continental-scale drivers of soil microbial extracellular polymeric substances

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Abstract

Extracellular polymeric substances (EPS) are key microbial residues that contribute to soil organic carbon (SOC) and promote soil aggregation. Yet, their abundance and large-scale controls have only begun to be investigated. We conduct extensive soil sampling across a European transect spanning diverse climates, bedrocks, and land uses. Average soil EPS content is 956 ± 55 µg g-1 soil (n= 92 sites), with EPS-carbon (EPS-C) contributing 1.6 ± 0.1% to SOC. Bedrock influences EPS content, EPS-C contribution to SOC, and the EPS-C/microbial biomass carbon (MBC) ratio, whereas land use mainly affects the latter two. The EPS-C/MBC ratio is negatively correlated with microbial growth and carbon use efficiency, and increases under water deficit, while EPS increases with MBC, clay content, and exchangeable calcium. Our results demonstrate that EPS represents a functionally important microbial residue, regulated by climatic, edaphic, microbial, and land-use factors, with significant implications for soil carbon cycling and sequestration.

Data availability

The EPS data generated in this study are provided in Supplementary Data 1, including measurements of EPS polysaccharides, EPS proteins, total EPS, EPS polysaccharides-C, EPS proteins-C, EPS-C, and associated site information (site, region, land use, bedrock, latitude, longitude and elevation). A compiled dataset of EPS data extracted from previous studies is provided in Supplementary Data 2. Raw data underlying all figures are available in the Source Data files accompanying this paper. A subset of additional environmental variables and microbial data used in this study is available under restricted access due to data ownership and sharing restrictions; access may be granted by the corresponding author and with permission from the data owners. The raw environmental datasets cannot be made publicly available for this reason. Summary statistics of climatic, edaphic, plant and microbial variables (mean, SD and sample size, n) are provided in Supplementary Table 7. Processed datasets used for figure generation, together with summary statistics necessary to interpret the analyses and reproduce the presented figures, are included within the Supplementary Information and Source Data files. Source data are provided with this paper.

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Acknowledgements

This research was funded in whole or in part by the Austrian Science Fund (FWF) [grant DOI: 10.55776/P28037] (W.W.). This study was further supported by the National Key Research and Development Program of China (No. 2023YFD2200404 and No. 2021YFD2200402/3) (H.R.), and the program of China Scholarship Council (No. 202308320320) (K.S.). For open access purposes, the author has applied a CC BY public copyright license to any author-accepted manuscript version arising from this submission.

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Authors and Affiliations

  1. Department of Ecology, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, China

    Ke Shi 
    (石珂) & Honghua Ruan 
    (阮宏华)

  2. Division of Terrestrial Ecosystem Research, Department of Microbiology and Ecosystem Science, Center of Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria

    Ke Shi 
    (石珂), Qing Zheng, Lisa Noll, Shasha Zhang, Yuntao Hu & Wolfgang Wanek

  3. German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany

    Ke Shi 
    (石珂)

  4. Institute of Biology, Leipzig University, Leipzig, Germany

    Ke Shi 
    (石珂)

  5. State Key Laboratory of Soil and Water Conservation and Desertification Control, College of Grassland Agriculture, Northwest A&F University, Yangling, Shaanxi, China

    Baorong Wang 
    (王宝荣)

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  1. Ke Shi 
    (石珂)

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  2. Qing Zheng
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  3. Baorong Wang 
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  4. Lisa Noll
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  7. Honghua Ruan 
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Contributions

K.S. drafted the manuscript, conducted laboratory work, and analyzed and interpreted the data. Q.Z., B.W., L.N., S.Z., and Y.H. performed laboratory work, contributed to data analysis, and assisted in manuscript editing. H.R. reviewed and revised the manuscript. W.W. designed the study, interpreted the data, and contributed to manuscript editing. All authors contributed to the manuscript and approved the final version for publication.

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Correspondence to
Honghua Ruan 
(阮宏华) or Wolfgang Wanek.

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Nature Communications thanks Stefano Manzoni, Redmile-Gordon Marc and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. A peer review file is available.

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Shi, K., Zheng, Q., Wang, B. et al. Continental-scale drivers of soil microbial extracellular polymeric substances.
Nat Commun (2026). https://doi.org/10.1038/s41467-026-70068-0

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