Department of Life Science and Environmental Biochemistry/Life and Industry Convergence Research Institute, Pusan National University, Miryang, 50463, Republic of Korea.
Avian Disease Division, Animal and Plant Quarantine Agency, Gimcheon, 39660, Republic of Korea.
J Environ Manage. 2022 Nov 1;321:115929. doi: 10.1016/j.jenvman.2022.115929. Epub 2022 Aug 17.
Cracking and erosion are critical factors that reduce the mechanical properties and stability of concrete structures and soil, respectively. They are recognized worldwide as severe disasters causing the collapse of many structures including stone heritage and dams, and landslides. Therefore, it is essential to propose effective and environment-friendly management methods to prevent them. Carbonatogenesis has recently received considerable attention as a reliable biological process for remediating cracks in calcareous structures, stabilizing loose soils, and sequestering CO in the environment. Isolating and characterizing carbonatogenic bacteria with excellent performance is crucial for applying this process to the field of environmental and civil engineering. The aim of this study was to isolate new CaCO-precipitating bacteria and investigate various properties for their use as bioconsolidants. Furthermore, the possibility of restoring damaged structures and stabilizing loose sandy soil using isolated strain was investigated. Strain LC13 with urease and CaCO-precipitating activity was isolated from limestone cave soil in Korea and identified as Arthrobacter sulfureus by phenotypic characterization and 16S rRNA gene analysis. Although cell growth was observed after an adaptation period at pH 11, strain LC13 grew well at pH 7-11, indicating alkali tolerance. The optimal conditions for CaCO precipitation were 1.0% yeast extract, 2.5% urea, 0.35% NaHCO, and 400 mM CaCl, with an initial pH of 6.5 at 30 °C. Under optimized conditions, maximal CaCO (22.92 ± 0.14 g/l) precipitated after 3 days, which was 10.8-fold higher than the value in a urea-CaCl medium. CaCO precipitation by strain LC13 was associated with an increased pH due to ureolysis and protein deamination. Using an optimized medium as a cementation solution, strain LC13 completely remediated 340-760 μm wide cracks over 3 days, and also restored the spalling of concrete surfaces. Furthermore, the sand treated with LC13 solidified with a surface strength of 14.9 kPa. Instrumental analysis confirmed that the crystals precipitated were a mixture of CaCO polymorphs composed of rhombohedral calcite and spherical vaterite. These results suggest that A. sulfureus LC13 may be useful for implementing sustainable biorestoration and environmental management technologies such as the in situ remediation of structural cracks and in situ prevention of soil erosion.
开裂和侵蚀分别是降低混凝土结构和土壤力学性能和稳定性的关键因素。它们被公认为是导致许多结构（包括石质遗产和水坝以及滑坡）倒塌的严重灾害。因此，提出有效且环保的管理方法来防止它们至关重要。碳酸化作用最近作为一种修复钙质结构裂缝、稳定疏松土壤和在环境中固定 CO 的可靠生物过程而受到广泛关注。分离和表征具有优异性能的碳酸化细菌对于将该过程应用于环境和土木工程领域至关重要。本研究的目的是分离新的碳酸钙沉淀细菌，并研究其作为生物固结剂的各种性质。此外，还研究了使用分离菌株修复受损结构和稳定松散砂壤土的可能性。从韩国石灰石洞穴土壤中分离出具有脲酶和碳酸钙沉淀活性的菌株 LC13，并通过表型特征和 16S rRNA 基因分析鉴定为节杆菌属（Arthrobacter sulfureus）。尽管在 pH 11 下适应期后观察到细胞生长，但菌株 LC13 在 pH 7-11 下生长良好，表明具有耐碱性。碳酸钙沉淀的最佳条件为 1.0%酵母提取物、2.5%尿素、0.35% NaHCO 和 400 mM CaCl，初始 pH 为 6.5，温度为 30°C。在最佳条件下，最大碳酸钙（22.92±0.14 g/L）沉淀在 3 天后，比尿素-CaCl 培养基中的值高 10.8 倍。菌株 LC13 沉淀碳酸钙与由于脲酶解和蛋白脱氨导致的 pH 升高有关。使用优化的培养基作为胶结溶液，菌株 LC13 在 3 天内完全修复了 340-760 µm 宽的裂缝，并且还修复了混凝土表面的剥落。此外，用 LC13 处理的砂固化后表面强度为 14.9 kPa。仪器分析证实，沉淀的晶体是由菱面体方解石和球形文石组成的碳酸钙多晶型混合物。这些结果表明，节杆菌属（Arthrobacter sulfureus）LC13 可能有助于实施可持续的生物修复和环境管理技术，例如结构裂缝的原位修复和土壤侵蚀的原位预防。
