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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2018-477
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2018-477
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 16 Nov 2018

Research article | 16 Nov 2018

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Kinetics of calcite precipitation by ureolytic bacteria under aerobic and anaerobic conditions

Andrew C. Mitchell1,2, Erika J. Espinosa-Ortiz2, Stacy L. Parks2,3, Adrienne Phillips2,4, Alfred B. Cunningham2,4, and Robin Gerlach2,3 Andrew C. Mitchell et al.
  • 1Department of Geography and Earth Sciences, Interdisciplinary Centre for Environmental Microbiology, Aberystwyth University, SY23 3DB, UK
  • 2Center for Biofilm Engineering, Montana State University, Bozeman, MT, 59717, USA
  • 3Department of Chemical and Biological Engineering, Montana State University, Bozeman, MT 59717, USA
  • 4Department of Civil Engineering, Montana State University, Bozeman, MT 59717, USA

Abstract. The kinetics of urea hydrolysis (ureolysis) and induced calcium carbonate (CaCO3) precipitation for engineering use in the subsurface was investigated under aerobic conditions using Sporosarcina pasteurii (ATCC strain 11859) as well as Bacillus sphaericus strains 21776 and 21787. All bacterial strains showed ureolytic activity inducing CaCO3 precipitation aerobically. Rate constants not normalized to biomass demonstrated slightly higher rate coefficients for both ureolysis (kurea) and CaCO3 precipitation (kprecip) for B. sphaericus 21776 (kurea = 0.10 ± 0.03h−1, kprecip = 0.60 ± 0.34h−1) compared to S. pasteurii (kurea = 0.07 ± 0.02h−1, kprecip = 0.25 ± 0.02h−1). B. sphaericus 21787 showed little ureolytic activity but was still capable of inducing some CaCO3 precipitation. Cell growth appeared to be inhibited during the period of CaCO3 precipitation. TEM images suggest this is due to the encasement of cells and was reflected in lower kurea values observed in the presence of dissolved Ca. However, biomass re-growth could be observed after CaCO3 precipitation ceased, which suggests that ureolysis-induced CaCO3 precipitation is not necessarily lethal for the entire population. The kinetics of ureolysis and CaCO3 precipitation with S. pasteurii were further analyzed under anaerobic conditions. Rate coefficients obtained in anaerobic environments were comparable to those under aerobic conditions, however no cell growth was observed under anaerobic conditions with NO3, SO42− and Fe3+ as potential terminal electron acceptors. These data suggest that the initial rates of ureolysis and ureolysis-induced CaCO3 precipitation are not significantly affected by the absence of oxygen but that long-term ureolytic activity might require the addition of suitable electron acceptors. Such variations in the ureolytic capabilities and associated rates of CaCO3 precipitation between strains must be fully considered in subsurface engineering strategies that utilize microbial amendments.

Andrew C. Mitchell et al.
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Andrew C. Mitchell et al.
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Short summary
Microbially induced carbonate mineral precipitation (MICP) is a natural process which is also being investigated for subsurface engineering applications including radionuclide immobilisation and microfracture plugging. We demonstrate that rates of MICP from microbial urea hydrolysis (ureolysis) vary with different bacterial strains, but rates are similar in both oxygenated and oxygen-free conditions. Ureolyisis MICP is therefore a viable biotechnology in the predominately oxygen free subsurface.
Microbially induced carbonate mineral precipitation (MICP) is a natural process which is also...
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