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Front. Microbiol. | doi: 10.3389/fmicb.2018.02785

Extreme geochemical conditions and dispersal limitation retard primary succession of microbial communities in gold tailings

  • 1University of Western Australia, Australia
  • 2University of Alberta, Canada
  • 3The University of Queensland, Australia

Microbial community succession in tailings materials is poorly understood at present, and likely to be substantially different from similar processes in natural primary successional environments due to the unusual geochemical properties of tailings and the isolated design of tailings storage facilities. This is the first study to evaluate processes of primary succession in microbial communities colonising unamended tailings, and compare the relative importance of stochastic (predominantly dust-borne dispersal) and deterministic (strong selection pressures from extreme geochemical properties) processes in governing community assembly rates and trajectories to those observed in natural environments. Dispersal-based recruitment required > 6 months to shift microbial community composition in unamended, field-weathered gold tailings; and in the absence of targeted inoculants, recruitment was dominated by salt- and alkali-tolerant species. In addition, cell numbers were less than 106 cells/g tailings until > 6 months after deposition. Laboratory experiments simulating microbial cell addition via dust revealed that high (> 6 months’ equivalent) dust addition rates were required to effect stabilisation of microbial cell counts in tailings. In field-weathered tailings, topsoil addition during rehabilitation works exerted a double effect, acting as a microbial inoculant and correcting geochemical properties of tailings. However, microbial communities in rehabilitated tailings remained compositionally distinct from those of reference soils in surrounding environments. pH, water extractable Mg, and water extractable Fe emerged as major controls on microbial community composition in the field-weathered gold tailings. Overall, this study highlights the need for application of targeted microbial inoculants to accelerate rates of microbial community succession in tailings, which are limited primarily by slow dispersal due to physical and spatial isolation of tailings facilities from inoculant sources; and for geochemical properties of tailings to be amended to moderate values to encourage microbial community diversification and succession,

Keywords: Microbial community succession, tailings, Rehabilitation, microbial community assembly, Dispersal, Microbial colonisation

Received: 05 Sep 2018; Accepted: 30 Oct 2018.

Edited by:

Jennifer Glass, Georgia Institute of Technology, United States

Reviewed by:

Brandon Briggs, University of Alaska Anchorage, United States
Lauren M. Seyler, Woods Hole Oceanographic Institution, United States  

Copyright: © 2018 Santini, Raudsepp, Hamilton and Nunn. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Talitha C. Santini, University of Western Australia, Perth, Australia, t.santini@uq.edu.au