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

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 (k_urea) and CaCO₃ precipitation (k_precip) for B. sphaericus 21776 (k_urea=0.10±0.03 h^-1, k_precip=0.60±0.34 h^-1) compared to S. pasteurii (k_urea=0.07±0.02 h^-1, k_precip=0.25±0.02 h^-1), though these differences were not statistically significantly different. 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. Transmission electron microscopy (TEM) images suggest this is due to the encasement of cells and was reflected in lower k_urea values observed in the presence of dissolved Ca. However, biomass regrowth 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 was 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 $$NO_3^-,SO_4^{2-}$$ or 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. 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.

Authors:

Mitchell, Andrew C. ^[1]; Espinosa-Ortiz, Erika J. ^[2]; Parks, Stacy L. ^[2]; Phillips, Adrienne J. ^[2]; Cunningham, Alfred B. ^[2]; Gerlach, Robin  ^[2]

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+ Show Author Affiliations

1. Aberystwyth Univ. (United Kingdom); Montana State Univ., Bozeman, MT (United States)
2. Montana State Univ., Bozeman, MT (United States)

Publication Date:

Thu May 23 00:00:00 EDT 2019

Research Org.:

Montana State Univ., Bozeman, MT (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE); European Union Marie-Curie Reintegration Grant; National Science Foundation (NSF)

OSTI Identifier:

1614106

Grant/Contract Number:  

FC26-04NT42262; FE0004478; FE0009599; FG02-08ER46527; FG02-09ER64758; 277005; DMS-0934696; W911NF0510255

Resource Type:

Accepted Manuscript

Journal Name:

Biogeosciences (Online)

Additional Journal Information:

Journal Name: Biogeosciences (Online); Journal Volume: 16; Journal Issue: 10; Journal ID: ISSN 1726-4189

Publisher:

European Geosciences Union

Country of Publication:

United States

Language:

English

Subject:

58 GEOSCIENCES; 59 BASIC BIOLOGICAL SCIENCES; environmental sciences & ecology; geology