Improvement of Biomineralization of Sporosarcina pasteurii as Biocementing Material for Concrete Repair by Atmospheric and Room Temperature Plasma Mutagenesis and Response Surface Methodology

Influencing factors on ureolytic microbiologically induced calcium carbonate precipitation for biocementation

Microbiologically induced calcium carbonate precipitation (MICP) is a technique that has received a lot of attention in the field of geotechnology in the last decade. It has the potential to provide a sustainable and ecological alternative to conventional consolidation of minerals, for example by the use of cement. From a variety of microbiological metabolic pathways that can induce calcium carbonate (CaCO₃) precipitation, ureolysis has been established as the most commonly used method. To better understand the mechanisms of MICP and to develop new processes and optimize existing ones based on this understanding, ureolytic MICP is the subject of intensive research. The interplay of biological and civil engineering aspects shows how interdisciplinary research needs to be to advance the potential of this technology. This paper describes and critically discusses, based on current literature, the key influencing factors involved in the cementation of sand by ureolytic MICP. Due to the complexity of MICP, these factors often influence each other, making it essential for researchers from all disciplines to be aware of these factors and its interactions. Furthermore, this paper discusses the opportunities and challenges for future research in this area to provide impetus for studies that can further advance the understanding of MICP.

Highlighting Bacteria with Calcifying Abilities Suitable to Improve Mortar Properties

Biomineralization, the use of microorganisms to produce calcium carbonate, became a green solution for application in construction materials to improve their strength and durability. The calcifying abilities of several bacteria were investigated by culturing on a medium with urea and calcium ions. The characterization of the precipitates from bacterial cultures was performed using X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The formation of carbonate crystals was demonstrated by optical and scanning electron microscopy. Water absorption and compressive strength measurements were applied to mortars embedded with sporal suspension. The efficiency of the supplementation of mortar mixtures with bacterial cells was evaluated by properties, namely the compressive strength and the water absorption, which are in a relationship of direct dependence, the increase in compressive strength implying the decrease in water absorption. The results showed that Bacillus subtilis was the best-performing bacterium, its introduction into the mortar producing an increase in compressive strength by 11.81% and 9.50%, and a decrease in water absorption by 11.79% and 10.94%, after 28 and 56 days of curing, respectively, as compared to standards. The exploitation of B. subtilis as a calcifying agent can be an interesting prospect in construction materials.

Biomineralization Induced by Cells of Sporosarcina pasteurii: Mechanisms, Applications and Challenges

Biomineralization has emerged as a novel and eco-friendly technology for artificial mineral formation utilizing the metabolism of organisms. Due to its highly efficient urea degradation ability, Sporosarcina pasteurii(S. pasteurii) is arguably the most widely investigated organism in ureolytic biomineralization studies, with wide potential application in construction and environmental protection. In emerging, large-scale commercial engineering applications, attention was also paid to practical challenges and issues. In this review, we summarize the features of S. pasteurii cells contributing to the biomineralization reaction, aiming to reveal the mechanism of artificial mineral formation catalyzed by bacterial cells. Progress in the application of this technology in construction and environmental protection is discussed separately. Furthermore, the urgent challenges and issues in large-scale application are also discussed, along with potential solutions. We aim to offer new ideas to researchers working on the mechanisms, applications and challenges of biomineralization.