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Original Research ARTICLE

Front. Microbiol. | doi: 10.3389/fmicb.2020.00286

Identification of persistent sulfidogenic bacteria in shale gas produced waters Provisionally accepted The final, formatted version of the article will be published soon. Notify me

  • 1School of Earth and Environmental Sciences, University of Manchester, United Kingdom
  • 2Department of Soil and Crop Sciences, College of Agricultural Sciences, Colorado State University, United States
  • 3Other, United Kingdom

Produced waters from hydraulically fractured shale formations give insight into the microbial ecology and biogeochemical conditions down-well. This study explores the potential for sulfide production by persistent microorganisms recovered from produced water samples collected from the Marcellus shale formation. Hydrogen sulfide is highly toxic and corrosive, and can lead to the formation of “sour gas” which is costly to refine. Furthermore, microbial colonisation of hydraulically fractured shale could result in formation plugging and a reduction in well productivity. It is vital to assess the potential for sulfide production in persistent microbial taxa, especially when considering the trend of reusing produced waters as input fluids, potentially enriching for problematic microorganisms. Using most probable number counts and 16S rRNA gene sequencing, multiple viable strains of bacteria were identified from stored produced waters, mostly belonging to the Genus Halanaerobium, that were capable of growth via fermentation, and produced sulfide when supplied with thiosulfate. No sulfate-reducing bacteria were detected through culturing, despite the detection of relatively low numbers of sulfate-reducing lineages by high-throughput 16S rRNA gene sequencing. These results demonstrate that sulfidogenic produced water populations remain viable for years post production and, if left unchecked, have the potential to lead to natural gas souring during shale gas extraction.

Keywords: Thiosulfate-reducing bacteria, Biogenic sulfide, Halanaerobium, non- conventional gas, Microbiology

Received: 04 Oct 2019; Accepted: 07 Feb 2020.

Copyright: © 2020 Cliffe, Nixon, Taylor, Boothman, Wilkins, Wrighton, Lloyd, Eden and Daly. 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: Mrs. Lisa Cliffe, School of Earth and Environmental Sciences, University of Manchester, Manchester, M13 9PL, Manchester, United Kingdom, Lisa.Cliffe@manchester.ac.uk