Jiangsu Key Laboratory of Atmospheric Environment Monitoring and Pollution Control (AEMPC), Collaborative Innovation Center of Atmospheric Environment and Equipment Technology (CIC-AEET), Nanjing University of Information Science &Technology, Nanjing, 210044, China.
School of Geography and Environmental Sciences, University of Reading, Reading, RG6 6AH, UK.
World J Microbiol Biotechnol. 2024 Jun 3;40(7):229. doi: 10.1007/s11274-024-04038-3.
Biocementation, driven by ureolytic bacteria and their biochemical activities, has evolved as a powerful technology for soil stabilization, crack repair, and bioremediation. Ureolytic bacteria play a crucial role in calcium carbonate precipitation through their enzymatic activity, hydrolyzing urea to produce carbonate ions and elevate pH, thus creating favorable conditions for the precipitation of calcium carbonate. While extensive research has explored the ability of ureolytic bacteria isolated from natural environments or culture conditions, bacterial synergy is often unexplored or under-reported. In this study, we isolated bacterial strains from the local eutrophic river canal and evaluated their suitability for precipitating calcium carbonate polymorphs. We identified two distinct bacterial isolates with superior urea degradation ability (conductivity method) using partial 16 S rRNA gene sequencing. Molecular identification revealed that they belong to the Comamonas and Bacillus genera. Urea degradation analysis was performed under diverse pH (6,7 and 8) and temperature (15 °C,20 °C,25 °C and 30 °C) ranges, indicating that their ideal pH is 7 and temperature is 30 °C since 95% of the urea was degraded within 96 h. In addition, we investigated these strains individually and in combination, assessing their microbially induced carbonate precipitation (MICP) in silicate fine sand under low (14 ± 0.6 °C) and ideal temperature 30 °C conditions, aiming to optimize bio-mediated soil enhancement. Results indicated that 30 °C was the ideal temperature, and combining bacteria resulted in significant (p ≤ 0.001) superior carbonate precipitation (14-16%) and permeability (> 10 m/s) in comparison to the average range of individual strains. These findings provide valuable insights into the potential of combining ureolytic bacteria for future MICP research on field applications including soil erosion mitigation, soil stabilization, ground improvement, and heavy metal remediation.
生物矿化作用是一种强大的技术，通过脲酶细菌及其生化活性来稳定土壤、修复裂缝和进行生物修复。脲酶细菌通过酶促反应将尿素水解为碳酸根离子并提高 pH 值，从而为碳酸钙的沉淀创造有利条件，在碳酸钙沉淀中起着至关重要的作用。虽然广泛的研究已经探索了从自然环境或培养条件中分离出的脲酶细菌的能力，但细菌协同作用往往未被探索或报道较少。在这项研究中，我们从当地富营养化河流渠道中分离出细菌菌株，并评估了它们沉淀碳酸钙多晶型物的适用性。我们通过部分 16S rRNA 基因测序，鉴定出两株具有优异尿素降解能力（电导率法）的细菌分离株。分子鉴定表明它们属于粪产碱杆菌属和芽孢杆菌属。在不同 pH（6、7 和 8）和温度（15°C、20°C、25°C 和 30°C）范围内进行了尿素降解分析，结果表明它们的理想 pH 值为 7，温度为 30°C，因为在 96 小时内有 95%的尿素被降解。此外，我们还单独和组合研究了这些菌株，评估了它们在硅酸盐细砂中的微生物诱导碳酸钙沉淀（MICP），在低温（14 ± 0.6°C）和理想温度 30°C 条件下，旨在优化生物介导的土壤增强。结果表明，30°C 是理想的温度，与单独使用细菌相比，细菌组合可显著提高碳酸钙沉淀（14-16%）和渗透率（>10 m/s）（p≤0.001）。这些发现为未来 MICP 研究提供了有价值的见解，包括在现场应用中减轻土壤侵蚀、稳定土壤、改善地面和修复重金属等领域。
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