Capturing the unknown microbial players and genes involved in the cycling of arsenic and antimony in Northern peatland soils

Project description

Increased concentrations of the toxic metalloids arsenic and antimony are encountered in peatlands for a variety of reasons, including input of contaminated ground- or surface water. Mining operations can lead to increased concentrations of arsenic and antimony in peatlands when those are used for mine water treatment, as it is a common practice in Finland. Previous studies of microbial transformations of arsenic and antimony in treatment peatlands at a gold mine in Finnish Lapland indicated, that microbial transformations of arsenic and antimony play indeed an important role in contaminant removal. Moreover, (methyl-)thiolated and methylated arsenic species were detected in the treatment peatlands, arsenic species that have not been detected in many peatlands to date.

However, the studies also revealed many gaps in our understanding of microbial cycling of arsenic and antimony in peatlands, and of the pathways behind the observed transformations of arsenic and antimony. Moreover, it is largely unresolved how arsenic- and antimony-metabolizing microbial communities adapt to high contaminant concentrations in peatlands in Northern climate. Peatlands with naturally high arsenic concentrations pose an ideal site for comparison to reveal differences and similarities in the microbial community composition of peatlands with a long and a short contamination history.

Thus, this project aims to (i) compare the (active) microbial communities and arsenic/antimony-cycle genes in peatlands with different lengths of exposure to arsenic and antimony in high concentrations by metagenomics and –transcriptomics, (ii) resolve pathways in the cycling of arsenic and antimony in peatlands that are so far not sufficiently understood, (iii) identify active microorganisms and genes involved arsenic and antimony cycling and removal in peat soil, (iv) assess the natural changes in microbial activity as well as arsenic and antimony speciation in different seasons, and (v) isolate microorganisms with potential for use in bioremediation of arsenic and antimony contaminated waters and soils. The knowledge gained during this project will deepen our understanding of microbial arsenic and antimony cycling in peatlands and in situ activity of microbial communities involved in contaminant removal from mine waters.

Microbial cycling of As (A) and Sb (B) in peat soils.

Microbial cycling of As (A) and Sb (B) in peat soils. The cycles depict the most important microbially catalyzed processes (highlighted) assumed for the studied treatment peatlands (TP) based on existing data from previous studies. Formation of thioarsenates and methylthiolated As species is not completely understood to date. Thiolated and methylated Sb species were not detected in the TPs. Thus, the project focuses on the processes of arsenite/antimonite oxidation, arsenate/antimonate reduction, thioarsenate formation, and formation of methylated and methylthiolated As species.

Central hypothesis of the project

Arsenic and antimony are metabolized in different ways and by different microorganisms in peat soils. So-far unresolved pathways and unknown microbial key players in peatland arsenic and antimony cycling can be exploited for remediation of mine waters.

Project goals

  1. Identification of novel genes involved in As and Sb transformation which are not targeted by currently available primer systems
  2. Identification of active microorganisms and processes involved in As and Sb transformation
  3. Investigation of the seasonality of As and Sb in Kittilä mine treatment peatlands
  4. Identification and isolation of microorganisms with As biovolatilization and bioaccumulation properties

Project tasks

The project will be implemented in 5 workpackages:

  1. Metagenomes and metatranscriptomes of microbial communities in As and Sb contaminated peat
  2. Seasonal variations in As/Sb cycling processes, microbial activity and microbial communities
  3. Resolving pathways involved in As and Sb turnover in peatlands
  4. Labeling and identification of active As/Sb metabolizing microbes in laboratory pilot systems
  5. Identification and isolation of microorganisms with potential for As/Sb bioremediation

Project collaborators

In this project, we collaborate with experts in the field to achieve the best possible results. Collaborators included:

  • Prof. Marja Tiirola, Environmental Microbiology Group, University of Jyväskylä, Finland
  • Prof. Britta Planer-Friedrich, Environmental Geochemistry Group, University of Bayreuth, Germany
  • Prof. Marcus Horn, Soil Microbiology Research Group, Leibniz University of Hannover, Germany
  • Prof. Tim Urich, Bacterial Physiology Department, University of Greifswald, Germany
  • Prof. David Berry, Department of Microbiology and Ecosystem Science, Research Network Chemistry Meets Microbiology, University of Vienna, Austria
  • Doc. Anna-Maria Pirttilä, Symbiotic host-microbe interactions, Department of Ecology and Genetics, University of Oulu, Finland

Project news

We are looking for a PhD candidate (starting September 2020). Application deadline May 31st 2020. Apply here.

The project was presented at the 4th Thünen Symposium on Soil Metagenomics 11.-13.12. in Braunschweig, Germany. See the poster here!

Last updated: 17.4.2020