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.

Influence of native ureolytic microbial community on biocementation potential of Sporosarcina pasteurii

Microbially induced calcium carbonate precipitation (MICP)/Biocementation has emerged as a promising technique for soil engineering applications. There are chiefly two methods by which MICP is applied for field applications including biostimulation and bioaugmentation. Although bioaugmentation strategy using efficient ureolytic biocementing culture of Sporosarcina pasteurii is widely practiced, the impact of native ureolytic microbial communities (NUMC) on CaCO3 mineralisation via S. pasteurii has not been explored. In this paper, we investigated the effect of different concentrations of NUMC on MICP kinetics and biomineral properties in the presence and absence of S. pasteurii. Kinetic analysis showed that the biocementation potential of S. pasteurii is sixfold higher than NUMC and is not significantly impacted even when the concentration of the NUMC is eight times higher. Micrographic results revealed a quick rate of CaCO3 precipitation by S. pasteurii leading to generation of smaller CaCO3 crystals (5–40 µm), while slow rate of CaCO3 precipitation by NUMC led to creation of larger CaCO3 crystals (35–100 µm). Mineralogical results showed the predominance of calcite phase in both sets. The outcome of current study is crucial for tailor-made applications of MICP.

A Comparative Study On Self-Healing Methods of Concretes By Sporosarcina Pasteurii Bacteria

Biological methods (adding bacteria to the concrete mixtures) among the most recently investigated procedures increase the durability of concrete and repair concrete cracks. In the present study, different biological methods were used to heal the cracks of concrete and the most suitable method was subsequently introduced. For this purpose, the culture medium and bacterial nutrient inside the concrete mixes and curing solution were separately studied. The effect of air-entrained agent and various sources of calcium salts as the bacterial nutrient on the healing process was also studied. The results showed that the use of bacterial nutrient inside the concrete mixes has an affirmative impact on the mechanical properties and self-healing characteristics of concretes. With the simultaneous use of Sporosarcina pasteurii bacteria and calcium nitrate-urea or calcium chloride-urea as a bacterial nutrient in the concrete mixture, the 28 days compressive strength of concrete increases by 23.4% and 7.5%, respectively, which is due to calcium carbonate precipitation. The use of bacterial cells, nutrients, and culture in the concrete mixture provided the ability to heal wide cracks where the healing time is significantly reduced. On the other hand, separation of the bacterial culture medium slightly reduced the self-healing performance of concrete.

COMPARAÇÃO DE BIOMASSA VEGETAL E ANIMAL EM BIOARGAMASSA

O uso de microrganismos em meio líquido para o processo de biocimentação, favorece a continuidade do crescimento bacteriano. Entretanto se este demora para ser usado, para de crescer rapidamente, levando a morte celular. Este estudo comparou duas formas de produção de uma biomassa, capaz de armazenar os microrganismos em estado de latência mantendo a viabilidade para posterior utilização. Aqui foi descrito o preparo de biomassas, feitas com materiais orgânicos e bactéria Sporosarcina pasteurii (CCT 0538 ATCC 1185). Foram testadas biomassas de origem animal (esterco de aves) e vegetal (ervilhaca - Vicia villosa Roth). Ambas biomassas mantiveram a viabilidade dos microrganismos, sendo que a vegetal foi mais eficiente apresentando maior crescimento bacteriano após a revitalização. Para teste foram moldados corpos de prova referência (sem biomassa) e também com cada uma delas, e depois de 28 dias ensaiados a tração e compressão. A resistência a tração apresentou um aumento de 41,2 % (biomassa animal) e de 44,7 % (biomassa vegetal). Na resistência a compressão o aumento foi de 37,8 % (biomassa animal) e de 38,8 % (biomassa vegetal), comparados a argamassa de referencia (sem adição de microrganismo).