Comprehensive Profiling of Microbiologically Induced CaCO3 Precipitation by Ureolytic Bacillus Isolates from Alkaline Soils

Abstract

Microbiologically induced CaCO3 precipitation (MICP) is a well-known bio-based solution with application in environmental, geotechnical, and civil engineering. The significance of the MICP has increased explorations of process efficiency and specificity via natural bacterial isolates. In this study, comprehensive profiling of five soil ureolytic Bacillus strains was performed through a newly formed procedure that involved six steps from selection and identification, through kinetic study, to the characterization of the obtained precipitates, for the first time. To shorten the whole selection procedure of 43 bioagents with the MICP potential, Standard Score Analysis was performed and five selected bacteria were identified as Bacillus muralis, B. lentus, B. simplex, B. firmus, and B. licheniformis by the MALDI-TOF mass spectrometry. Despite following the targeted activity, kinetic studies were included important aspects of ureolysis and the MICP such as cell concentration, pH profiling, and reduction in calcium ion concentration. At the final step, characterization of the obtained precipitates was performed using FTIR, XRD, Raman, DTA/TGA, and SEM analysis. Although all tested strains showed significant potential in terms of precipitation of calcite or calcite and vaterite phase, the main differences in the MICP behavior can be observed at the bacterial strain level. B. licheniformis showed favorable behavior compared to the reference Sporosarcina pasteurii DSM 33.

New Exopolysaccharides Produced by Bacillus licheniformis 24 Display Substrate-Dependent Content and Antioxidant Activity

“…B. licheniformis is a Gram-positive, motile, non-pathogenic bacterium ubiquitously spread in natural habitats. As it is associated with plant material, it can be easily isolated from soil, water and the rhizosphere [ 1 , 23 , 24 , 25 , 26 ], but it can also be found on the feathers of terrestrial and aquatic bird species, and in marine water [ 27 ]. B. licheniformis is widely used in industry, horticulture and pharmacy.…”

Modification of Surfaces with Vaterite CaCO3 Particles

“…Hence, the applications of these bacterial strains that have been used in CaCO 3 mineralization bode well in the biomedical and environmental fields [ 88 ]. Intriguingly, the scientific relevant literature has reported aragonite and calcite as the most common bacterial carbonates, while this analysis observed only calcite and vaterite in all tested samples; this can suggest that precipitation of vaterite might be more common than expected by rather quick recrystallisation of vaterite to calcite in aqueous media [ 89 ].…”

Relationship between Bacterial Contribution and Self-Healing Effect of Cement-Based Materials

“…In view of bacterial life in these conditions, it is necessary to ensure the use of a bacterial strain which is tolerant of a high amount of salt during the SH effect. Some bacteria with a strong precipitating effect are reported as highly tolerant strains to the chloride present, and belong to Bacillus genera [ 114 , 115 ]. The situation is similar regarding sulphate attack on the concrete matrix.…”