The browser you are using is not supported by this website. All versions of Internet Explorer are no longer supported, either by us or Microsoft (read more here: https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Please use a modern browser to fully experience our website, such as the newest versions of Edge, Chrome, Firefox or Safari etc.

Default user image.

Margarida Soares

Postdoc

Default user image.

Can heavy metal pollution stress reduce microbial carbon-use efficiencies?

Author

  • Margarida Soares
  • Sandra Rabow
  • Johannes Rousk

Summary, in English

The fate of soil organic matter (OM) is determined by its microbial use for growth or respiration. Many environmental factors influence microbial OM use, including the presence of contaminants and toxins in the environment, such as heavy metals. We evaluated short- and long-term responses of microbial processes to metal contamination by estimating biomass concentrations and growth rates of bacteria and fungi, respiration, and the resulting microbial carbon-use efficiencies (CUE), and microbial turnover times. We sampled O-horizon from a gradient in boreal forest soils exposed to long-term heavy metal contamination arising from industrial point source since the 1930s to assess long-term effects on soil microorganisms. To estimate microbial responses to short-term metal exposure, additions of Cu were used. Bacterial growth rates and respiration rates decreased in response to long-term metal contamination, while fungal growth rates were unaffected, without changes in CUEs. Bacterial biomass concentrations were independent of soil metal concentrations while fungal and total biomass decreased. Thus, turnover times for bacteria were slowed while fungal turnover times were accelerated by metal pollution. Bacterial growth was inhibited and fungal growth stimulated by experimental Cu additions, with bigger effect sizes in contaminated sites. We interpreted the low rates of growth but high biomass in collected soil samples to indicate that the fungal community included a large mycorrhizal fraction. Although Cu additions decreased the overall microbial OM-use (i.e., the sum of fungal and bacterial growth and total respiration), they also increased the CUE. In conclusion, fungal OM-use was less sensitive than bacterial to metal pollution and the CUE was unaffected. Microbial decomposer communities in contaminated soils were also able to maintain higher CUE when challenged with new metal additions. Our results imply that microbial communities align their trait compositions to environmental challenges, and that this can mitigate the reduction in microbial carbon-use efficiencies that often is expected to occur from environmental stress.

Department/s

  • Centre for Environmental and Climate Science (CEC)
  • BECC: Biodiversity and Ecosystem services in a Changing Climate
  • Functional ecology
  • Aquatic Ecology
  • Microbial Biogeochemistry in Lund
  • Microbial Ecology

Publishing year

2024-08

Language

English

Publication/Series

Soil Biology and Biochemistry

Volume

195

Document type

Journal article

Publisher

Elsevier

Topic

  • Soil Science
  • Environmental Sciences

Keywords

  • Bacteria
  • Copper
  • Fungi
  • Heavy metal contamination
  • Microbial carbon use efficiency

Status

Published

Research group

  • Aquatic Ecology
  • Microbial Biogeochemistry in Lund
  • Microbial Ecology

ISBN/ISSN/Other

  • ISSN: 0038-0717