Sub-standard soils are of great concern worldwide due to diverse economic losses and the possibility of severe environmental hazards ranging from catastrophic landslides, building collapse, and erosion to loss of lives and properties. This study explored the potential of urease-producing bacteria, Bacillus cereus and Bacillus paramycoides, to stabilise sub-standard soil bio-stabilisation. The maximum urease activity measured by B. cereus and B. paramycoides was 665 U/mL and 620 U/mL, respectively. B. cereus and B. paramycoides precipitated 943 ± 57 mg/L and 793 ± 51 mg/L of CaCO₃ at an optical density (425 nm) of 1.01 and 1.09 and pH 8.83 and 8.59, respectively, after 96 hours of incubation. SEM microstructural analysis of the precipitated CaCO₃ revealed crystals of various sizes (2.0–23.0 µm) with different morphologies. XRD analysis confirmed that the precipitated CaCO₃ comprised calcite and aragonite crystals. SEM analysis of the microstructure of organic and sandy clay soils treated with B. cereus and B. paramycoides showed the formation of bio-precipitated calcium carbonate deposits on the soil particles (biocementing soil grains), with B. cereus precipitating more CaCO₃ crystals with a better biocementing effect compared to B. paramycoides. Overall, the experimental results attributed CaCO₃ formation to bacterial-associated processes, suggesting that soil ureolytic bacteria are potentially useful to stabilise sub-standard soil.

• Achal, V., Mukerjee, A., & Reddy, M. S. (2013). Biogenic treatment improves the durability and remediates the cracks of concrete structures. Construction and Building Materials, 48, 1-5. https://doi.org/10.1016/j.conbuildmat.2013.06.061

• Akyol, E., Bozkaya, O., & Dogan, N. M. (2017). Strengthening sandy soils by microbial methods. Arab Journal of Geoscience, 10, Article 327. https://doi.org/10.1007/s12517-017-3123-9

• Algaifi, H. A., Sam, A. R. M., Bakar, S. A., Abidin, R. Z., & Shahir, S. (2020). Screening of native ureolytic bacteria for self-healing in cementitious materials. In IOP Conference Series: Material Science and Engineering (Vol. 849, pp. 1-8). IOP Publishing. https://doi.org/10.1088/1757-899X/849/1/012074

• Alonso, M. J. C., Ortiz, C. E. L., Perez, S. O. G., Narayanasamy, R., Miguel, G. D. J. F. S., Hernández, H. H., & Balagurusamy, N. (2018). Improved strength and durability of concrete through metabolic activity of ureolytic bacteria. Environmental Science and Pollution Research, 25, 21451-21458. https://doi.org/10.1007/s11356-017-9347-0

• Al-Thawadi, S., & Cord-Ruwisch, R. (2012). Calcium carbonate crystals formation by ureolytic bacteria isolated from Australian soil and sludge. Journal of Advanced Science and Engineering Research, 2, 12-26.

• Anitha, V., Abinaya, K., Prakash, S., Rao, A. S., & Vanavil, B. (2018). Bacillus cereus KLUVAA mediated biocement production using hard water and urea. Chemical and Biochemical Engineering Quarterly, 32(2), 257-266. https://doi.org/10.15255/CABEQ.2017.1096

• Badiee, H., Sabermahani, M., Tabandeh, F., & Javadi, A. S. (2019). Application of an indigenous bacterium in comparison with Sporosarcina pasteurii for improvement of fine granular soil. International Journal of Environmental Science and Technology, 16(12), 8389-8400. https://doi.org/10.1007/s13762-019-02292-9

• Bang, S. S., Galinat, J. K., & Ramakrishnan, V. (2001). Calcite precipitation induced by polyurethane-immobilized Bacillus pasteurii. Enzyme and Microbial Technology, 28(4–5), 404–409. https://doi.org/10.1016/S0141-0229(00)00348-3

• Bang, S. S., Lippert, J. J., Yerra, U., & Mulukutla, S. (2010). Microbial calcite, a bio-based smart nanomaterial in concrete remediation. International Journal of Smart and Nano Materials, 1(1), 28-39. https://doi.org/10.1080/19475411003593451

• Bernardi, D., Dejong, J. T., Montoya, B. M., & Martinez, B. C. (2014). Bio-bricks: Biologically cemented sandstone bricks. Construction and Building Materials, 55, 462-469. https://doi.org/10.1016/j.conbuildmat.2014.01.019

• Bibi, S., Oualha, M., Ashfaq, M. Y., Suleiman, M. T., & Zouari, N. (2018). Isolation, differentiation and biodiversity of ureolytic bacteria of Qatari soil and their potential in microbially induced calcite precipitation (MICP) for soil stabilization. RSC Advances, 8(11), 5854-5863. https://doi.org/10.1039/C7RA12758H

• Bzura, J., & Koncki, R. (2019). A mechanized urease activity assay. Enzyme and Microbial Technology, 123, 1-7. https://doi.org/10.1016/j.enzmictec.2019.01.001

• Chahal, N., Rajor, A., & Siddique, R. (2011). Calcium carbonate precipitation by different bacterial strains. African Journal of Biotechnology, 10(42), 8359-8372. https://doi.org/10.5897/ajb11.345

• Chang, I., Im, J., & Cho, G. C. (2016). Introduction of microbial biopolymers in soil treatment for future environmentally-friendly and sustainable geotechnical engineering. Sustainability, 8(3), Article 251. https://doi.org/10.3390/su8030251

• Chang, R., Kim, S., Lee, S., Choi, S., Kim, M., & Park, Y. (2017). Calcium carbonate precipitation for CO2 storage and utilization: A Review of the carbonate crystallization and polymorphism. Frontiers in Energy Research, 5, Article 17. https://doi.org/10.3389/fenrg.2017.00017

• Cheng, L., Shahin, M. A., & Cord-Ruwisch, R. (2014). Bio-cementation of sandy soil using microbially induced carbonate precipitation for marine environments. Geotechnique, 64(12), 1010-1013. https://doi.org/10.1680/geot.14.T.025

• Choi, S. G., Wang, K., Wen, Z., & Chu, J. (2017). Mortar crack repair using microbial induced calcite precipitation method. Cement and Concrete Composites, 83, 209-221. https://doi.org/10.1016/j.cemconcomp.2017.07.013

• Cizer, O., Van Balen, K., Elsen, J., & Van Gemert, D. (2008). Crystal morphology of precipitated calcite crystals from accelerated carbonation of lime binders. In 2nd International Conference on Accelerated Carbonation for Environmental and Materials Engineering (ACEME08) (pp. 149-158). University of Rome.

• Dadda, A., Geindreau, C., Emeriault, F., du Roscoat, S. R., Filet, A. E., & Garandet, A. (2018). Characterization of contact properties in biocemented sand using 3D X-ray micro-tomography. Acta Geotechnica, 14, 597-613. https://doi.org/10.1007/s11440-018-0744-4

• Dardau, A. A., Mustafa, M., & Abdaziz, N. A. (2021). Microbial-induced calcite precipitation: A milestone towards soil improvement. Malaysian Applied Biology Journal, 50(1), 11-27. https://doi.org/10.55230/mabjournal.v50i1.8

• Dhami, K. N., Mukherjee, A., & Reddy, M. S. (2016). Micrographical , minerological and nano-mechanical characterisation of microbial carbonates from urease and carbonic anhydrase producing bacteria. Ecological Engineering, 94, 443-454. https://doi.org/10.1016/j.ecoleng.2016.06.013

• Dhami, N. K., Reddy, M. S., & Mukherjee, M. S. (2013). Biomineralization of calcium carbonates and their engineered applications: A review. Frontiers in Microbiology, 4, 314-327. https://doi.org/10.3389/fmicb.2013.00314

• Filet, A. E., Gutjahr, I., Garandet, A., Viglino, A., Béguin, R., Sibourg, O., Monier, J. M., Martins, J., Oxarango, L., Spadini, L., Geindreau, C., Emeriault F., & Perthuisot, S. C. (2020). BOREAL, Bio-reinforcement of embankments by biocalcification. In E3S Web of Conferences (Vol. 195, p. 05001). EDP Sciences.. https://doi.org/10.1051/e3sconf/202019505001

• Ghosh, T., Bhaduri, S., Montemagno, C., & Kumar, A. (2019). Sporosarcina pasteurii can form nanoscale calcium carbonate crystals on cell surface. Plos One, 14(1), Article e0210339. https://doi.org/10.1371/journal.pone.0210339

• Grice, J. D. (2005). The structure of spurrite, tilleyite and scawtite, and relationships to other silicate-carbonate minerals. The Canadian Mineralogist, 43(5), 1489-1500. https://doi.org/10.2113/gscanmin.43.5.1489

• Helmi, F. M., Elmitwalli, H. R., Elnagdy, S. M., & El-Hagrassy, A. F. (2016). Calcium carbonate precipitation induced by ureolytic bacteria Bacillus licheniformis. Ecological Engineering, 90, 367-371. https://doi.org/10.1016/j.ecoleng.2016.01.044

• Hoang, T., Alleman, J., Cetin, B., Ikuma, K., & Choi, S. G. (2019). Sand and silty sand soil stabilization using bacterial enzyme induced calcite precipitation (BEICP). Canadian Geotechnical Journal, 56(6), 808-822. https://doi.org/10.1139/cgj-2018-0191

• Imran, M. A., Kimura, S., Nakashima, K., Evelpidou, N., & Kawasaki, S. (2019). Feasibility study of native ureolytic bacteria for biocementation towards coastal erosion protection by MICP method. Applied Sciences, 9(20), Article 4462. https://doi.org/10.3390/app9204462

• Ivanov, V., Stabnikov, V., Stabnikova, O., & Ahmed, Z. (2020). Biocementation technology for construction of artificial oasis in sandy desert. Journal of King Saud University - Engineering Sciences, 32(8), 491-494. https://doi.org/10.1016/j.jksues.2019.07.003

• Jiang, N. J, Tang, C. S, Hata, T., Courcelles, B., Dawoud, O., & Singh, D. N. (2020). Bio-mediated soil improvement: The way forward. Soil Use and Management, 36(2), 185-188. https://doi.org/10.1111/sum.12571

• Jiang, N. J., Yoshioka, H., Yamamoto, K., & Soga, K. (2016). Ureolytic activities of a urease-producing bacterium and purified urease enzyme in the anoxic condition: Implication for subseafloor sand production control by microbially induced carbonate precipitation (MICP). Ecological Engineering, 90, 96-104. https://doi.org/10.1016/j.ecoleng.2016.01.073

• Kakelar, M. M., Ebrahimi, S., & Hosseini, M. (2016). Improvement in soil grouting by biocementation through injection method. Asia-Pacific Journal of Chemical Engineering, 11(6), 930-938. https://doi.org/10.1002/apj.2027

• Keykha, H. A., Asadi, A., & Zareian, M. (2017). Environmental factors affecting the compressive strength of microbiologically induced calcite precipitation treated soil. Geomicrobiology Journal, 34(10), 889-894. https://doi.org/10.1080/01490451.2017.1291772

• Kim, G., & Youn, H. (2016). Microbially induced calcite precipitation employing environmental isolates. Materials, 9(6), Article 468. https://doi.org/10.3390/ma9060468

• Kim, G., Kim, J., & Youn, H. (2018). Effect of temperature , pH , and reaction duration on microbially induced calcite precipitation. Applied Sciences, 8(8), Article 1277. https://doi.org/10.3390/app8081277

• Kim, J. H., & Lee, J. Y. (2019). An optimum condition of MICP indigenous bacteria with contaminated wastes of heavy metal. Journal of Material Cycles and Waste Management, 21, 239-247. https://doi.org/10.1007/s10163-018-0779-5

• Li, D., Tian, K. L., Zhang, H. L., Wu, Y. Y., Nie, K. Y., & Zhang, S. C. (2018). Experimental investigation of solidifying desert aeolian sand using microbially induced calcite precipitation. Construction and Building Materials, 172, 251-262. https://doi.org/10.1016/j.conbuildmat.2018.03.255

• Li, M., Fu, Q. L., Zhang, Q., Achal, V., & Kawasaki, S. (2015). Bio-grout based on microbially induced sand solidification by means of asparaginase activity. Scientific Reports, 5, Article 16128. https://doi.org/10.1038/srep16128

• Liu, B., Xie, Y. H., Tang, C. S., Pan, X. H., Jiang, N. J., Singh, D. N., Cheng, Y. J., & Shi, B. (2021). Bio-mediated method for improving surface erosion resistance of clayey soils. Engineering Geology, 293, Article 106295. https://doi.org/10.1016/j.enggeo.2021.106295

• Liu, Y., Chen, Y., Huang, X., & Wu, G. (2017). Biomimetic synthesis of calcium carbonate with different morphologies and polymorphs in the presence of bovine serum albumin and soluble starch. Materials Science and Engineering: C, 79, 457–464. https://doi.org/10.1016/j.msec.2017.05.085

• Luo, M., & Qian, C. X. (2016). Performance of two bacteria-based additives used for self-healing concrete. Journal of Materials in Civil Engineering, 28(12), Article 04016151. https://doi.org/10.1061/(asce)mt.1943-5533.0001673

• Makinda, J., Gungat, L., Rao, N. S. V. K., & Sulis, S. (2018). Compressibility behaviour of Borneo tropical peat stabilized with lime-sand column. International Journal on Advanced Science, Engineering and Information Technology, 8(1), 172-177. https://doi.org/10.18517/ijaseit.8.1.4169

• Miftah, A., Tirkolaei, H. K., & Bilsel, H. (2020). Biocementation of calcareous beach sand using enzymatic calcium carbonate precipitation. Crystals, 10(10), Article 888. https://doi.org/10.3390/cryst10100888

• Morsdorf, G., & Kaltwasser, H. (1989). Ammonium assimilation in Proteus vulgaris, Bacillus pasteurii, and Sporosarcina ureae. Archives of Microbiology. 152, 125-131. https://doi.org/10.1007/BF00456089

• Mortensen, B. M., Haber, M. J., Dejong, J. T., Caslake, L. F., & Nelson, D. C. (2011). Effects of environmental factors on microbial induced calcium carbonate precipitation. Journal of Applied Microbiology, 111(2), 338-349. https://doi.org/10.1111/j.1365-2672.2011.05065.x

• Muthukkumaran, K., & Shashank, B. S. (2016). Durability of microbially induced calcite precipitation (MICP) treated cohesionless soils. Japanese Geotechnical Society Special Publication, 2(56), 1946-1949. https://doi.org/10.3208/jgssp.IND-23

• Mwandira, W., Nakashima, K., & Kawasaki, S. (2017). Bioremediation of lead-contaminated mine waste by Pararhodobacter sp. based on the microbially induced calcium carbonate precipitation technique and its effects on strength of coarse and fine grained sand. Ecological Engineering, 109(Pt. A), 57-64. https://doi.org/10.1016/j.ecoleng.2017.09.011

• Mwandira, W., Nakashima, K., Kawasaki, S., Ito, M., Sato, T., Igarashi, T., Chirwa, M., Banda, K., Nyambe, I., Nakayama, S., Nakata, H., & Ishizuka, M. (2019). Solidification of sand by Pb(II)-tolerant bacteria for capping mine waste to control metallic dust: Case of the abandoned Kabwe Mine, Zambia. Chemosphere, 228, 17-25. https://doi.org/10.1016/j.chemosphere.2019.04.107

• Nawarathna, T. H. K., Nakashima, K., & Kawasaki, S. (2018). Enhancement of microbially induced carbonate precipitation using organic biopolymer. International Journal of Geomate, 14(41), 7-12. https://doi.org/10.21660/2018.41.7223

• Nawarathna, T. H. K., Nakashima, K., & Kawasaki, S. (2019). Chitosan enhances calcium carbonate precipitation and solidification mediated by bacteria. International Journal of Biological Macromolecules, 133, 867-874. https://doi.org/10.1016/j.ijbiomac.2019.04.172

• Nething, C., Smirnova, M., Gröning, J. A. D., Haase, W., Stolz, A., & Sobek, W. (2020). A method for 3D printing bio-cemented spatial structures using sand and urease active calcium carbonate powder. Materials and Design, 195, Article 109032. https://doi.org/10.1016/j.matdes.2020.109032

• Omoregie, A. I., Ngu, L. H., Ong, D. E. L., & Nissom, P. M. (2019). Low-cost cultivation of Sporosarcina pasteurii strain in food-grade yeast extract medium for microbially induced carbonate precipitation (MICP) application. Biocatalysis and Agricultural Biotechnology, 17, 247-255. https://doi.org/10.1016/j.bcab.2018.11.030

• Omoregie, A., Khoshdelnezamiha, G., Ong, D. E. L., & Nissom, P. M. (2017). Microbial-induced carbonate precipitation using a sustainable treatment technique. International Journal of Service Management and Sustainability, 2(1), 17-31. http://dx.doi.org/10.24191/ijsms.v2i1.6045

• Oral, Ç. M., & Ercan, B. (2018). Influence of pH on morphology, size and polymorph of room temperature synthesized calcium carbonate particles. Powder Technology, 339, 781-788. https://doi.org/10.1016/j.powtec.2018.08.066

• Oshiki, M., Araki, M., Hirakata, Y., Hatamoto, M., Yamaguchi, T., & Araki, N. (2018). Ureolytic prokaryotes in soil: Community abundance and diversity. Microbes and Environments, 33(2), 230-233. https://doi.org/10.1264/jsme2.ME17188

• Osinubi, K. J., Eberemu, A. O., Gadzama, E. W., & Ijimdiya, T. S. (2019). Plasticity characteristics of lateritic soil treated with Sporosarcina pasteurii in microbial-induced calcite precipitation application. SN Applied Sciences, 1, Article 829. https://doi.org/10.1007/s42452-019-0868-7

• Pablo, A. C. M. S., Lee, M, Graddy, C. M. R., Kolbus, C. M., Khan, M., Zamani, A., Martin, N., Acuff, C., Dejong, J. T., Gomez, M. G., & Nelson, D. C. (2020). Meter-scale biocementation experiments to advance process control and reduce impacts: Examining spatial control, ammonium by-product removal, and chemical reductions. Journal of Geotechnical and Geoenvironmental Engineering, 146(11), 1-14. https://doi.org/10.1061/(ASCE)GT.1943-5606.0002377

• Park, S. J., Park, Y. M., Chun, W. Y., Kim, W. J., & Ghim, S. Y. (2010). Calcite-forming bacteria for compressive strength improvement in mortar. Journal of Microbiology and Biotechnology, 20(4), 782-788.

• Qabany, A. A., Soga, K., & Santamarina, C. (2011). Factors affecting efficiency of microbially induced calcite precipitation. Journal of Geotechnical and Geoenvironmental Engineering, 138(8), 992-1001. https://doi.org/10.1061/(asce)gt.1943-5606.0000666

• Rabenhorst, M., Buchanan, A., Morozov, E., Shay, J., & Mack, S. (2020). Field test for identifying problematic red parent materials. Soil Science Society of American Journal, 84(3), 1006-1010. https://doi.org/10.1002/saj2.20066

• Renner, L. D., & Weibel, D. B. (2011). Physicochemical regulation of biofilm formation. MRS Bulletin, 36, 347-355. https://doi.org/10.1557/mrs.2011.65

• Richardson, A., Coventry, K. A., Forster, A. M., & Jamison, C. (2014). Surface consolidation of natural stone materials using microbial induced calcite precipitation. Structural Survey, 32(3), 265-278. https://doi.org/10.1108/SS-07-2013-0028

• Ritchey, E. L., McGrath, J. M., & Gehring, D. (2015). Determining soil texture by feel. Agriculture and Natural Resources Publications.

• Sapar, N. I. F., Matlan, S. J., Mohamad, H. M., Alias, R., & Ibrahim, A. (2020). A study on physical and morphological characteristics of tropical peat in Sabah. International Journal of Advanced Research in Engineering and Technology (IJARET), 11(11), 542-553.

• Sharma, M., Satyam, N., & Reddy, K. R. (2021). Investigation of various gram-positive bacteria for MICP in Narmada Sand, India. International Journal of Geotechnical Engineering, 15(2), 220-234. https://doi.org/10.1080/19386362.2019.1691322

• Singh, M. J., Weiqiang, F., Dong-Sheng, X., & Borana, L. (2020). Experimental study of compression behavior of Indian black cotton soil in oedometer condition. International Journal of Geosynthetics and Ground Engineering, 6, Article 30. https://doi.org/10.1007/s40891-020-00207-0

• Sinha, S., & Chattopadhyay. S. (2016). A study on application of renewable energy technologies for mitigatting the adverse environmental impacts generated from power generation units in Himalayan region. International Journal for Innovative Research in Science & Technology, 3(1), 212-232.

• Srivastava, S., Bharti, R. K., & Thakur, I. S. (2014). Characterization of bacteria isolated from palaeoproterozoic metasediments for sequestration of carbon dioxide and formation of calcium carbonate. Environmental Science and Pollution Research, 22, 1499-1511. https://doi.org/10.1007/s11356-014-3442-2

• Svane, S., Sigurdarson, J. J., Finkenwirth, F., Eitinger, T., & Karring, H. (2020). Inhibition of urease activity by different compounds provides insight into the modulation and association of bacterial nickel import and ureolysis. Scientific Reports, 10, Article 8503. https://doi.org/10.1038/s41598-020-65107-9

• Taner, F. M., Martin, R. F. & Gault, R. A. (2013). The mineralogy of skarns of the spurrite-merwinite subfacies, sanidinite facies, Guneyce-ikizdere area, eastern black sea, Turkey. The Canadian Mineralogist, 51(6), 893-911. https://doi.org/10.3749/canmin.51.6.893

• Tang, C. S., Yin, L. Y., Jiang, N. J., Zhu, C., Zeng, H., Li, H., & Shi, B. (2020). Factors affecting the performance of microbial-induced carbonate precipitation (MICP) treated soil: A review. Environmental Earth Sciences, 79, Article 94. https://doi.org/10.1007/s12665-020-8840-9

• Terzis, D., & Laloui, L. (2019). Cell-free soil bio-cementation with strength, dilatancy and fabric characterization. Acta Geotechnica, 14, 639-656. https://doi.org/10.1007/s11440-019-00764-3

• Towner, G. D. (1974). The assessment of soil texture from soil strength measurements. Journal of Soil Science, 25(3), 298-306. https://doi.org/10.1111/j.1365-2389.1974.tb01125.x

• Wahab, N., Talib, M. K. A., & Rohani, M. M. (2019). An introduction of tropical peat and its history of shear strength in Malaysia. International Journal of Civil Engineering and Technology (IJCIET), 10(5), 695-705.

• Wang, Z., Zhang, N., Cai, G., Jin, Y., Ding, N., & Shen, D. (2017). Review of ground improvement using microbial induced carbonate precipitation (MICP). Marine Georesources and Geotechnology, 35(8), 1135-1146. https://doi.org/10.1080/1064119X.2017.1297877

• Warren, L. A., Maurice, P. A., Parmar, N., & Ferris, F. G. (2001). Microbially mediated calcium carbonate precipitation: Implications for interpreting calcite precipitation and for solid-phase capture of inorganic contaminants. Geomicrobiology Journal, 18(1), 93-115. https://doi.org/10.1080/01490450151079833

• Wath, R. B., & Pusadkar, S. S. (2016). Soil improvement using microbial: A review. In T. Thyagaraj (Ed.), Lecture Notes in Civil Engineering: Vol. 14. Ground Improvement Techniques and Geosynthetics (pp. 329-335). Springer. https://doi.org/10.1007/978-981-13-0559-7_37

• Wei, S., Cui, H., Jiang, Z., Hao, L., He, H., & Fang, N. (2015). Biomineralization processes of calcite induced by bacteria isolated from marine sediments. Brazilian Journal of Microbiology, 46(2), 455-464. https://doi.org/10.1590%2FS1517-838246220140533

• Wen, K., Li, Y., Amini, F., & Li, L. (2020). Impact of bacteria and urease concentration on precipitation kinetics and crystal morphology of calcium carbonate. Acta Geotechnica, 15, 17-27. https://doi.org/10.1007/s11440-019-00899-3

• Wiley, W. R., & Stokes, J. L. (1963). Effect of pH and ammonium ions on the permeability of Bacillus pasteurii. Journal of Bacteriology, 86, 1152-1156. https://doi.org/10.1128/jb.86.6.1152-1156.1963

• Wong, L. S. (2015). Microbial cementation of ureolytic bacteria from the genus Bacillus: A review of the bacterial application on cement based materials for cleaner production. Journal of Cleaner Production, 93, 5-17. https://doi.org/10.1016/j.jclepro.2015.01.019

• Wu, J., Wang, X. B., Wang, H. F., & Zeng, R. J. (2017). Microbially induced calcium carbonate precipitation driven by ureolysis to enhance oil recovery. RSC Advances, 7(59), 37382-37391. https://doi.org/10.1039/c7ra05748b

• Zhang, J., Zhao, C., Zhou, A., Yang, C., Zhao, L., & Li, Z. (2019). Aragonite formation induced by open cultures of microbial consortia to heal cracks in concrete: Insights into healing mechanisms and crystal polymorphs. Construction and Building Materials, 224, 815-822. https://doi.org/10.1016/j.conbuildmat.2019.07.129

• Zhu, T., & Dittrich, M. (2016). Carbonate precipitation through microbial activities in natural environment, and their potential in biotechnology: A review. Frontiers in Bioengineering and Biotechnology, 4, Article 4. https://doi.org/10.3389/fbioe.2016.00004