Bioprecipitation of calcium carbonate by Bacillus subtilis and its potential to self-healing in cement-based materials

Abstract

In recent years, biological mineralization has been implemented as a viable option for the elaboration of new building materials, protection and repair of concrete by self-healing, soil stabilization, carbon dioxide capture, and drug delivery. Biogenic mineralization of calcium carbonate (CaCO3) induced by bacterial metabolism has been proposed as an effective method. The objective of the present study was to characterize the bioprecipitation of CaCO3 crystals by Bacillus subtilis in a semi-solid system. The results show that CaCO3 crystals were produced by day 3 of incubation. The prevalent crystalline polymorph was calcite, and in a minor proportion, vaterite. The presence of amorphous material was also detected (amorphous CaCO3 (ACC)). Finally, the crystallinity index was 81.1%. This biogenic calcium carbonate does not decrease pH and does not yield chloride formation. Contrary, it increases pH values up to 10, which constitutes and advantage for implementations at reinforced concrete. Novel applications for biogenic calcium carbonate derived from Bacillus subtilis addressing self-healing, biocementation processes, and biorestoration of monuments are presented.

Bacteria-Induced Calcite Precipitation for Engineering and Environmental Applications

“…Inducing calcite precipitation in calcareous soils [7] 2020 B. subtilis Evaluating curing conditions on compressive strength and fber-reinforced concrete [46] 2020 Bacillus subtilis ATCC23857 Self-healing in cement-based materials [1] 2017, 2020…”

“…vulgaris ATCC29579 can remove the black crust deposits on marbles, which was comparatively better than the chemical cleaning method [88]. However, the BCP via the sulphur cycle is not appropriate for engineering applications because it is problematic to maintain the anaerobic conditions and H 2 S is also detrimental to the environment [1]. It is shown in the following chemical equations:…”

“…Bacteria-induced calcite precipitation (BCP) is the term for calcite synthesis at supersaturation circumstances and temperatures, which, because of the presence of bacterial cells and their metabolic activity, induce reactions that produce a variety of calcium carbonate polymorphs [1]. Organisms can secrete one or more metabolic products that react with divalent cations in their environment, resulting in mineral precipitation.…”

“…Until now, many bacteria have been used to illustrate the molecular mechanisms involved in the calcite precipitation with diferent morphologies [1,[15][16][17]. Typically, the type of bacterium selected for BCP depends on the specifc function and environmental factors.…”

Precipitación de carbonatos inducida microbiológicamente como potencial estrategia en la restauración de estructuras patrimoniales

“…La pared celular bacteriana generalmente se encuentra cargada negativamente, por ende, es capaz de enlazar en su superficie cationes divalentes como Ca 2+ o Mg 2+ . Por ejemplo, múltiples especies de bacterias (e.g., Bacillus subtilis) son capaces de promover la precipitación de CaCO 3 al convertir CO 2 en a través de la anhidrasa carbónica (AC), enzima que cataliza la formación de ácido carbónico a partir de anhídrido carbónico o dióxido de carbono y agua (Pérez and García 2020). En mayor detalle el mecanismo de precipitación inicia con la disolución de CO 2 gaseoso en agua, para formar CO 2 acuoso (Ecuación 2).…”