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Microbially induced calcite precipitation (MICP) or biocementation is a bio-mediated process that can be used to improve the engineering properties of granular soils through calcium carbonate precipitation. Although most commonly this process is accomplished using microbial urea hydrolysis, other microbial metabolic pathways can be used to enable biocementation with the potential to eliminate ammonium byproducts. Microbial organic acid oxidation presents one alternative pathway by which increases in solution carbonate species can be generated to enable calcium carbonate mineral formation. While past studies have considered the potential of this microbial pathway to enable biocementation for surficial applications, to date few studies have examined the feasibility of this pathway for subsurface applications wherein dissolved oxygen is more limited. In this study, 18 small-scale batch experiments were performed to investigate the ability of microbial organic acid oxidation to enable biocementation soil improvement. Experiments investigated the feasibility of using both acetate and citrate oxidation to mediate biocementation as well as the effect of differences in techniques used to supply dissolved oxygen, the effect of supplied growth factors, bicarbonate salt additions, and solution sampling frequency. Results suggest that aerobic oxidation of acetate and citrate can be used to enable calcium carbonate biocementation, though ensuring dissolved oxygen availability appears to be critical towards enabling this process.
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Surface-displayed silicatein-α enzyme in bioengineered E. coli enables biocementation and silica mineralization
Biocementation is an exciting biomanufacturing alternative to common cement, which is a significant contributor of CO2greenhouse gas production. In nature biocementation processes are usually modulated via ureolytic microbes, such asSporosarcina pasteurii,precipitating calcium carbonate to cement particles together, but these ureolytic reactions also produce ammonium and carbonate byproducts, which may have detrimental effects on the environment. As an alternative approach, this work examines biosilicification via surface-displayed silicatein-α in bio-engineeredE. colias anin vivobiocementation strategy. The surface-display of silicatein-α with ice nucleation protein is a novel protein fusion combination that effectively enables biosilicification, which is the polymerization of silica species in solution, from the surface ofE. colibacterial cells. Biosilicification with silicatein-α produces biocementation products with comparable compressive strength asS. pasteurii.This biosilicification approach takes advantage of the high silica content found naturally in sand and does not produce the ammonium and carbonate byproducts of ureolytic bacteria, making this a more environmentally friendly biocementation strategy.
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- Award ID(s):
- 1821389
- PAR ID:
- 10536718
- Publisher / Repository:
- Frontiers
- Date Published:
- Journal Name:
- Frontiers in Systems Biology
- Volume:
- 4
- ISSN:
- 2674-0702
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3389/fsysb.2024.1377188
